Everyday Science — Chapter 6

Physics in Daily Life — Units, Motion, Light and Sound, Heat, Electricity and Magnetism, and Nuclear Basics

Why this chapter matters: physics is the most formula-and-unit dense block in Everyday Science — the papers rarely ask for derivations, but they ask the same definitions, units and conversions again and again. Our verified banks hold 208 questions matching this topic by question text, and the weight sits exactly where this chapter puts it: light, sound and waves (68 questions) — above all sound in different media, the speed of sound and light, lenses, lasers and eclipses — followed by nuclear and energy sources (56) — Pakistan’s nuclear plants, solar cells, renewable vs non-renewable sources and hydroelectricity — motion, force and gravity (28), units and measurements (27), electricity and magnetism (24) and heat and thermodynamics (5). The chapter is built on Lecture 9 (Hammad Arshad), whose definitions and values are the papers’ own language; bank-only facts (silver as the best conductor, the hearing range, Pakistan’s nuclear plants) are added where the lecture is silent and flagged as such in Section 11. Measuring instruments get their full tables in Chapter 8 (Inventions, Discoveries & Instruments) — here they appear only where the physics needs them.

1. What physics is — and the scalar/vector split that organises everything

• Physics is the branch of science dealing with the properties of matter, energy and their mutual relationship.
• Nuclear physics deals with the atomic nucleus. Photometry is the measurement of light (photo = light, metry = measurement).
• The first sorting the papers demand — learn it before any formula:

• Trap in the banks: “which is not a vector-borne disease? → rabies” is a biology question that matched the word “vector” in counting — it is not physics, and it is not counted in the 208. Vector in physics always means magnitude + direction.

2. Units & measurements — the 7 SI bases, the prefixes, and the units banks ask

The 7 SI base quantities

• Bank checks on this table: “the normal temperature of the human body on the Kelvin scale → 310” (310 K ≈ 37 °C); “the unit for measuring electric current → ampere”; “1 metre = 100 cm = 10³ mm”; “how many pounds in one kilogram? → 2.2046”; “how many grams in one kilogram? → 1,000 g”.

The prefixes (10⁻¹⁸ to 10⁺¹⁸)

• atto, femto, pico, nano, micro, milli, centi, deci, deca, hecto, kilo, mega, giga, tera, peta, exa — sixteen prefixes, smallest to largest. The papers ask the sequence and the extremes (atto at 10⁻¹⁸, exa at 10⁺¹⁸).

The derived units the papers ask most

3. Motion — rest, distance, speed, acceleration, force

• Rest = a body not moving, in equilibrium. Motion = a body changes its state (of rest or motion).
• Distance = length of the path travelled, without direction → scalar. Displacement = the shortest directional distance from one point to another → vector. “What is measured by metre per second? → velocity” — speed and velocity share the unit m/s; direction is what separates them.
• Speed = distance covered in unit time (m/s). Velocity = rate of change of displacement.
• Acceleration = rate of change of velocity → vector, unit m/s². Gravitational acceleration g = 9.81 m/s² (constant, asked directly).
• Escape velocity = the velocity needed to escape Earth’s gravitational pull = 7 miles per second in the lecture’s units — the banks ask the same fact as 11.2 km/s and as 40,000 km/h. All three are the same number (7 mi/s ≈ 11.2 km/s ≈ 40,000 km/h); learn the set, not one form.
• Force = the quantity which moves or tries to move a body, unit Newton.
• Mass = scalar (kilogram); weight = vector (newton); weight = mass × g. The banks test this with the Moon: acceleration due to gravity on the Moon is 0.166 times Earth’s, so a man weighing 60 kg on Earth weighs 10 kg on the Moon (60 × 0.166 ≈ 10) — mass unchanged, weight changed.

Newton’s three laws

• Inertia = the property resisting change in a state of rest or uniform motion → scalar.

Momentum, torque, friction

• Momentum = product of mass and velocity (p = mv), unit Newton-second (N·s) → vector. Law of conservation of momentum: in an isolated system the total momentum before an event equals the total momentum after it. Angular momentum = moment of linear momentum.
• Torque = the turning effect of force, unit Newton-metre (N·m), τ = F × r, acting clockwise or anticlockwise.
• Friction = the force resisting relative motion of two surfaces in contact — the lecturer’s phrase, “a necessary evil”. It is reduced by changing sliding to rolling — the banks ask this exact conversion twice (“friction can be reduced by changing from sliding to rolling”). Friction between car tyres and the road is maximum when the car is screeching with brakes pressed hard.
• Work = force × displacement, unit joule. Energy = capability of doing work, unit joule. Kinetic energy = energy due to motion, KE = ½mv² — directly proportional to mass and to v², so doubling v makes KE 4×. Potential energy = energy due to height, PE = mgh — dam water is the example; in dams the chain is PE → mechanical → electrical.

4. Gravity — Newton, Archimedes, circular motion

• Law of gravitation: attraction between every two masses, experimentally confirmed. Where one mass is the Earth, the attraction is called gravity. The banks ask it as “who propounded the law of gravitation → Newton”, “gravity was discovered by → Newton”, and “who discovered the law of gravitation and three laws of motion → Sir Isaac Newton”. Galileo’s earlier experiments with falling bodies are the banks’ “first experiments with gravity” answer — Newton gave the law.
• Artificial gravity is created in a satellite by spinning it on its own axis — the banks ask this twice, including the purpose: to overcome the weightlessness experienced by astronauts.
• Centre of gravity = the point where the whole body’s weight acts.
• Archimedes’ principle: a body immersed in a liquid experiences an upward thrust equal to the weight of the liquid displaced — submarines are built on it.
• Centripetal force helps an object move in a circle; its opposite is centrifugal force (“antonym of centrifugal → centripetal”). The orbiting satellite’s centripetal force comes from the gravitational pull of the Earth; a car rounding a corner gets it from friction.
• Concurrent forces = forces acting at a single point.

5. Waves and sound — the biggest bank block in this chapter

• Frequency = number of cycles per second (hertz). v = fλ — frequency is inversely proportional to wavelength: higher frequency, shorter wavelength (very high frequency waves have shorter wavelengths — asked three ways). A tuning-fork calculation the banks repeat: frequency 300, wavelength 4 ft → velocity 1,200 ft/s (v = fλ).
• Waves are the medium to transport energy from one place to another. Mechanical waves need a medium; electromagnetic waves do not. That one distinction answers the most-asked sound question: sound cannot travel through a vacuum (asked four ways); sound travels faster in water than in air, and fastest through solids — steel, glass, wood (banks: “velocity of sound is largest in → steel rod”; “speed of sound is maximum through → glass”; “sound travels fastest through → steel”). Denser medium, faster sound.
• Speed of sound in air — the lecture’s figure is 1,235 km/h (≈ 343 m/s). The banks’ figures sit on the same scale at different temperatures: 332 m/s at 0 °C, about 330 m/s in dry air at 20 °C in one bank key (a rounded value). Rule: as temperature rises, the speed of sound rises — asked directly, twice. Do not let the 330/332/343 spread confuse you: they are the same speed measured at different temperatures, and the direction of change is what the papers test.
• Sound is a form of energy giving the sensation of hearing. A normal human ear hears 20 Hz – 20 kHz (bank fact); bats hear ultrasonic sound (bank fact). Normal conversation = 30–60 dB.
• Sound waves in air are longitudinal waves. When reflected sound mixes with the original, it is reverberation.
• Doppler effect = the shift in frequency of sound waves — higher as the source approaches, lower as it recedes.
• SONAR = Sound Navigation and Ranging — finds ocean depth and locates objects deep in the ocean.
• Radar uses radio waves; the velocity of radio waves = velocity of light. Radar also measures vehicle speed (police radar) and the distance to objects.
• The flash of lightning is seen before the thunder is heard because light travels much faster than sound — the banks’ classic application question.
• Electromagnetic spectrum order the papers test: red light has the longest wavelength, violet the shortest. Wien’s law (bank extra, one question): the wavelength of maximum energy is inversely proportional to the absolute temperature.

6. Light — speed, lenses, laser, and the three behaviours

• Speed of light in vacuum = 300 million m/s (3 × 10⁸ m/s) — asked directly, and as “travelling at the speed of light one can travel around the Earth 7 times in one second”.
• Reflection = bouncing back of light. Refraction = bending of light at the boundary of two media. Dispersion = splitting of light into its constituent colours. Diffraction is maximum at a sharp edge.
• Laser produces a beam of monochromatic coherent light — asked four ways. Bank extras: ruby is the usual laser material; argon laser is used for operating on glaucoma; laser-beam technology is used in optical disks.
• Spherical lenses: convex is thicker at the middle — it is the magnifying glass, used for long-sightedness, and in a photographic camera it forms an inverted, real image on the film. Concave is thicker at the sides, thinner in the middle; the lecture’s image summary for the lens pair is real, inverted, diminished.
• Telescope = for viewing distant objects; Newton devised the reflecting telescope. Quartz watches work on the piezoelectric effect. Illumination is measured in lux. Photometry (Section 1) is the measurement of light.
• Eclipses (taught here because the banks file them with light, and Chapter 1 taught the Sun–Moon geometry): solar eclipse = Moon between Sun and Earth (asked four ways); lunar eclipse occurs on a full moon.
• Trap in the banks: one bank paper keys “the speed of light is → 86,000 m/s”. That key is wrong against every other bank paper and the lecture — the standard answer is 300 million m/s. Take 300 million wherever it is offered.
• Devices the lecture lists under light: mobile phone, television, optical fibres.

7. Electricity — current, Ohm’s law, and the conversion machines

• Current = flow of electric charges. 1 ampere = 6.24 × 10¹⁸ charge carriers.
• Ohm’s law: V = IR — voltage directly proportional to current. Units: voltage = volt (V), current = ampere (I), resistance = ohm.
• Electrical power = energy supplied in unit time, unit watt, 1 W = 1 J/s; also P = W/t and P = F × v. 1 HP = 746 W.
• DC (direct current): frequency zero — constant, does not change direction. AC (alternating current): changes direction at regular intervals. AC → DC = rectifier; DC → AC = inverter. A galvanometer cannot use alternating current (bank fact).
• The four conversion machines — learn them as a square:

• Kirchhoff’s laws: KCL (conservation of charge): sum of currents entering a junction = sum leaving. KVL (conservation of energy): algebraic sum of voltages around any closed loop = zero. (One bank paper keys “the essence of Kirchhoff’s law” to the absorber–radiator statement — that is Kirchhoff’s law of thermal radiation, a different law with the same name; the circuit laws above are the lecture’s KCL/KVL.)
• Fuse wire protects the circuit when excess current flows — the wire melts; it is made of a tin and lead alloy, and for household mains it must have a low melting point.
• Faraday’s law deals with electromagnetic induction; the tape recorder works on this principle, and sound is recorded on tape as a magnetic field.
• Electric field = the field produced in the surrounding of charged particles.
• Coulomb’s law: the force between two charges is directly proportional to their magnitudes and inversely proportional to the square of the distance between them.

8. Magnetism, materials, and heat — the properties block

Magnets and fields

• North attracts south; like poles repel (“the North pole of a magnet repels → North Pole”). A magnet free to move points north–south because the Earth is a huge magnet (bank fact).
• Lenz’s law is a consequence of the law of conservation of energy.

Conductors, insulators, semiconductors

• Capacitor = a device that stores electric charge.
• Conductor = electricity passes easily — low resistance. Best conductor of electricity → silver (bank fact, asked five ways). Insulator = electricity cannot pass — rubber, plastic, glass; wood is the least conductor among common materials; iron is a bad insulator (i.e. a conductor). Silicon is not a conductor in the banks’ conductor/insulator sorting — it is a semiconductor (see below).
• Semiconductor = conductivity between insulator and conductor; silicon is the semiconductor material the banks name. Doping = adding impurity to a semiconductor. When temperature rises, a semiconductor’s resistance decreases (the opposite of a metal’s behaviour — a favourite trap).

Elasticity, viscosity, ductility

• Elasticity = the property of retaining shape — steel is more elastic than rubber (its stress/strain ratio is higher).
• Viscosity = internal resistance of fluids (thickness/stickiness) — water < honey. With rising temperature, the viscosity of gases increases and liquids decrease (bank fact).
• Young’s modulus = the relationship between stress and strain, SI unit pascal. Compressibility = reciprocal of bulk modulus; thermal resistance = reciprocal of thermal conductivity; resistance and conductance are reciprocals of each other.
• Ductile materials can be drawn into thin wires — copper, aluminium, mild steel, gold.

Thermodynamics and heat transfer

• Law of conservation of energy: energy can neither be created nor destroyed — only converted from one form to another; the total energy of an isolated system remains constant.
• Zeroth law of thermodynamics: if two systems are each in thermal equilibrium with a third system, they are in thermal equilibrium with each other (the temperature scale rests on this).
• Heat transfer, all three asked: conduction (direct contact), convection (actual motion of matter), radiation (electromagnetic waves). A bad emitter of radiation is a bad absorber.
• Electricity generation in general: mechanical → electrical via turbines/generators. Thermal plants burn fossil fuels.

9. Energy sources and nuclear basics — renewables, non-renewables, reactor vs bomb

• Renewable = recyclable via biological/chemical processes: wind, tidal, solar, geothermal, biomass, hydroelectric. Non-renewable = from fossil fuels (coal, natural gas, oil) — cannot be recycled. Burning fossil fuels emits CO₂ (bank fact).
• Solar: photons → electricity via solar panels; solar cells are mainly made of silicon, and the element required for solar-energy conversion is silicon. Wind energy is an example of kinetic energy. Hydroelectricity: hydroelectric : water :: solar : sun (bank analogy).
• Nuclear power plants use uranium-235; nuclear is the strongest energy type in the lecture’s ranking. Geiger–Muller tubes detect nuclear radiation. Radiation penetration order: gamma > beta > alpha — alpha is stopped by paper, beta by aluminium, and gamma is the most penetrating of the three (PMS Screening 2026 GK Grand Mock 20, Q32; mock-only bank row, no mark claimed). Reactor = controlled reaction; atomic bomb = uncontrolled reaction — the single distinction the papers ask. A nuclear bomb/reactor produces heat through a chain reaction; the moderator controls the chain reaction and boron rods absorb excess neutrons (bank facts). Enriched uranium is uranium with a high percentage of a particular isotope.
• Pakistan’s nuclear programme (bank facts, not in the lecture):
  • Pakistan Atomic Energy Commission (PAEC) established 1956; it is the organisation responsible for nuclear-power development in the country.
  • First nuclear power plant: KANUPP, Karachi — provided by Canada, capacity 136 MW in the banks’ key; banks ask both 1971 (operation started) and 1972 (established) — the plant went into operation in 1971 and is dated 1972 in the “established” papers. Read the question’s verb.
  • First nuclear reactor (research reactor — not a power plant): PARR-I, at PINSTECH, Nilore — supplied by the United States under the Atoms for Peace programme, went critical on 21 December 1965, a 5 MW pool-type research reactor (later converted to low-enriched fuel and upgraded to 10 MW). PARR-I is the answer when the question asks for the first reactor; KANUPP is the answer when it asks for the first nuclear power plant — see the trap in Section 13.
  • Second nuclear plant: Chashma, built with the help of China, near Chashma Barrage at Mithan Kot, capacity 325 MW (Chashma I), connected to the national grid in 2000; the banks call Chashma the biggest nuclear power station in Pakistan.
  • Pakistan’s first nuclear explosion: Chaghai (Raskoh, Balochistan) — the banks phrase it as Raskoh/Chaghai and Mekran coasts; the test site answer is Chaghai.
• Pakistan’s hydroelectricity (bank facts, overlapping Chapter PS-13’s dams): the oldest hydroelectric project is Malakand Dargai; Tarbela’s installed capacity 3,478 MW with a 70% share of hydroelectric production in the banks’ key, Mangla 20%, Warsak 4.8%; Neelum–Jhelum 969 MW near Muzaffarabad; Munda Dam on the Swat, 740 MW. These figures are the banks’ keys, not current installed capacities — answer the paper, not the present day.

10. Master tables — the whole chapter on two tables

Units and formulas at a glance

The conversion square and the material sorting

11. Rapid-fire one-liners

• Physics = properties of matter, energy and their mutual relationship; nuclear physics = atomic nucleus; photometry = measurement of light.
• Scalar (magnitude only): mass, time, distance, pressure; vector (+ direction): acceleration, velocity, displacement.
• 7 SI bases: time–second, length–metre, mass–kilogram, current–ampere, temperature–kelvin, substance–mole, luminous intensity–candela.
• Prefixes 10⁻¹⁸→10⁺¹⁸: atto, femto, pico, nano, micro, milli, centi, deci, deca, hecto, kilo, mega, giga, tera, peta, exa.
• Distance = path length, scalar; displacement = shortest directional distance, vector; rest = equilibrium; motion = state change.
• Speed unit = m/s; velocity = rate of change of displacement; escape velocity = 7 miles/sec = 11.2 km/s = 40,000 km/h.
• Acceleration unit = m/s² (vector); g = 9.81 m/s²; force unit = Newton; mass = scalar (kg), weight = vector (N), W = m × g.
• Newton: 1st = rest stays rest; 2nd = F = ma; 3rd = equal & opposite reaction; inertia = resists change, scalar.
• Momentum = m × v, unit N·s, vector; torque = turning effect of force, N·m, τ = F × r.
• Friction = resists relative motion (“necessary evil”); sliding → rolling reduces it.
• Artificial gravity = spinning satellite on its axis; centre of gravity = whole weight acts there.
• Gravitation = attraction between every two masses; with Earth → gravity.
• Archimedes = upward thrust = weight of displaced liquid → submarines.
• Centripetal = circular motion (opposite: centrifugal); concurrent forces = one point.
• Work = F × d, joule, 1 J = 1 N·m; energy = capability of doing work, joule.
• KE = ½mv² (v doubled → 4×); PE = mgh (dam water); dams: PE → mechanical → electrical.
• v = fλ; frequency inversely ∝ wavelength; mechanical waves need medium, EM waves don’t.
• Radar = radio waves; radio-wave speed = light speed; red = longest λ, violet = shortest.
• Sound = form of energy; conversation = 30–60 dB; sound speed in air = 1,235 km/h; Doppler = frequency shift; ear range 20 Hz–20 kHz.
• SONAR = Sound Navigation and Ranging (ocean depth + objects); sound speed rises with temperature; sound cannot travel through vacuum; sound fastest in solids (steel).
• Energy conservation: isolated system’s total energy constant; Lenz’s law follows from it; zeroth law = thermal equilibrium transitivity.
• Thermal resistance = 1 / thermal conductivity; resistance ↔ conductance reciprocals.
• 1 ampere = 6.24 × 10¹⁸ charge carriers; V = IR; V = volt, I = ampere, R = ohm.
• 1 W = 1 J/s; 1 HP = 746 W; P = W/t = F × v.
• DC = frequency zero, no direction change; AC = changes direction; AC→DC = rectifier, DC→AC = inverter.
• Motor = electrical → mechanical; generator = mechanical → electrical; transformer = static, frequency constant, ideal = power constant.
• Photovoltaic cell = solar → electricity (chemical process); Coulomb’s law = ∝ magnitudes, 1/∝ distance².
• Steel > rubber in elasticity; viscosity = internal fluid resistance, water < honey; Young’s modulus unit = pascal; compressibility = 1 / bulk modulus.
• Ductile = thin wires: copper, aluminium, mild steel, gold.
• Fuse = melts on excess current, tin + lead alloy; Faraday’s law = electromagnetic induction; tape recorder uses it.
• North attracts south; like poles repel; capacitor stores charge; conductor = low resistance; insulators = rubber, plastic, glass; best conductor = silver; semiconductor material = silicon.
• Doping = impurity in semiconductor; semiconductor conductivity between the two; temperature ↑ → resistance ↓.
• Light speed = 300 million m/s; laser = monochromatic coherent beam; diffraction max at sharp edge.
• Reflection = bounce back; dispersion = split into colours; refraction = bend at media boundary.
• Telescope = distant objects; quartz watch = piezoelectric effect; illumination unit = lux; solar eclipse = Moon between Sun and Earth; lunar eclipse = full moon.
• Convex lens = thicker middle (magnifying glass); concave = thicker sides; camera image = real, inverted.
• KCL = charge conserved (in = out at junction); KVL = energy conserved (loop voltages sum = zero).
• Reactor = controlled reaction, bomb = uncontrolled; Geiger–Muller detects radiation; nuclear plants use U-235, strongest energy type.
• Energy can’t be created/destroyed, only converted; renewables = wind, tidal, solar, geothermal, biomass, hydro; non-renewables = coal, gas, oil.
• Solar = photons → electricity via panels (silicon); conduction = contact, convection = matter motion, radiation = EM waves.
• PAEC = 1956; first nuclear plant = KANUPP, Karachi (Canada); second = Chashma (China); Chashma I = 325 MW, grid 2000; first research reactor = PARR-I, PINSTECH Nilore, 1965 (not a power plant — see Section 13).

12. Most-asked facts (from our verified past-paper banks)

• Light, sound & waves — 68 questions: sound in different media (fastest in steel/glass, faster in water than air, cannot travel through vacuum) asked a dozen ways; speed of sound vs temperature (rises with temperature; 332 m/s at 0 °C; 330 m/s dry air at 20 °C in one key); speed of light (300 million m/s; 7 Earth-circuits per second); lenses (convex = magnifying glass, long-sightedness, inverted real camera image); laser (monochromatic coherent beam, ruby, argon–glaucoma); eclipses (solar = Moon between Sun and Earth, lunar = full moon); frequency–wavelength (v = fλ, VHF shorter wavelength); Doppler, SONAR, radar (radio waves at light speed).
• Nuclear & energy sources — 56 questions: Pakistan’s nuclear plants dominate — KANUPP/Karachi first plant (Canada, 1971/1972, 136 MW), Chashma second plant (China, 325 MW, grid 2000, Mithan Kot), PAEC 1956, Chaghai test site; solar cells (silicon) asked five ways; renewable vs non-renewable sorting; chain reaction, moderator, boron rods; hydroelectricity shares (Tarbela 70%, Mangla 20%, Warsak 4.8%, Neelum–Jhelum 969 MW, Munda/Swat 740 MW).
• Motion, force & gravity — 28 questions after cleaning: Newton’s laws and gravitation (who gave them, inertia = first law, action–reaction = third); escape velocity (11.2 km/s, 40,000 km/h); friction (sliding → rolling, maximum with screeching brakes); centripetal force (satellite from Earth’s gravity, car from friction); kinetic energy (due to motion); artificial gravity (spinning on axis); Moon weight (0.166 × Earth).
• Units & measurements — 27 questions: SI units (energy = joule, pressure = pascal, charge = coulomb, current = ampere); horsepower = 746 W asked four ways; decibel (intensity of sound) asked four ways; metre conversions (1 m = 100 cm = 10³ mm; 1 kg = 1,000 g = 2.2046 lb); Kelvin body temperature (310 K).
• Electricity & magnetism — 24 questions: best conductor = silver asked five ways; conductor/insulator sorting (silicon not a conductor, iron a bad insulator, wood least conductor); fuse wire (low melting point); magnets (north repels north, Earth as a huge magnet); semiconductors (silicon); Kirchhoff, Coulomb, current-flow definitions.
• Heat & thermodynamics — 5 questions: thermal resistance = reciprocal of thermal conductivity; Lenz’s law as a consequence of energy conservation; viscosity of gases vs liquids with temperature; bad emitter = bad absorber.
• Taught from the lecture, no direct site-bank question-text match in this run’s count: the full 16-prefix sequence, the 7-base table as a set, torque’s τ = F × r, concurrent forces, Archimedes’ submarine link, the zeroth-law statement, Young’s modulus and compressibility reciprocals, the ductile-metals list, the motor/generator/transformer/photovoltaic square as a set, and the conduction/convection/radiation trio — the IBES Everyday Science capsule bank behind the chapter covers the physics rows. The practice set is filtered by tags at serve time.

13. Traps & confusions

• Escape velocity, three forms, one number: lecture 7 miles/sec = banks’ 11.2 km/s = banks’ 40,000 km/h. Convert, don’t memorise three separate facts.
• Sound speed, three numbers, one rule: lecture 1,235 km/h (≈ 343 m/s) vs banks’ 332 m/s at 0 °C and 330 m/s (dry air, 20 °C, rounded key). The numbers differ because the temperature differs; the tested rule is speed rises with temperature. Answer with the temperature the question names.
• Speed of light wrong key: one bank paper keys 86,000 m/s. Every other bank paper and the lecture give 300 million m/s. Take 300 million wherever offered.
• “Current” questions that are not physics: the raw count caught dozens of “current Prime Minister / current Chief Justice / current literacy rate” questions on the word “current” — none is counted in the 208. In physics, “current” means flow of electric charges unless the question says otherwise.
• Vector-borne disease is not a vector question: “which is not a vector-borne disease → rabies” matched the word “vector” and was removed. Physics vectors are magnitude + direction.
• Kirchhoff, two laws, one name: circuit KCL/KVL (charge/energy conservation) vs Kirchhoff’s thermal-radiation law (good absorber = good radiator). The lecture teaches the circuit laws; the absorber–radiator key is the other law.
• Silicon’s double role: silicon is the semiconductor material and the solar-cell material — so “which is not a conductor → silicon” and “solar cells are made of → silicon” are both right. Do not let one use of silicon cancel the other.
• KANUPP 1971 vs 1972: banks ask both years for the same plant — operation started 1971, “established” papers print 1972. Read the question’s verb before choosing.
• PARR-I vs KANUPP — reactor is not power plant: PARR-I (PINSTECH, 1965) is Pakistan’s first nuclear reactor — a research reactor that makes no commercial electricity. KANUPP (Karachi, 1971/1972) is the first nuclear power plant. One bank paper keys KANUPP to the bare wording “First nuclear reactor of Pakistan” — that key is the loose wording, not the distinction: if the question says power plant or power station, answer KANUPP; if it says research reactor or names PINSTECH, answer PARR-I.
• Hydroelectricity shares are bank keys, not today’s capacities: Tarbela 70% / Mangla 20% / Warsak 4.8% and the 462 MW nuclear-generating figure are the papers’ figures at the time they were set. Answer the paper, not the present day.
• Geothermal “strongest” vs nuclear “strongest”: the lecture calls both the strongest in different sections. The chapter keeps nuclear as the strongest energy type (energy density, U-235 plants) and drops the geothermal superlative — geothermal stays in the renewable list without a rank.
• Coulomb’s law, lecture shorthand vs standard: the lecture note phrases it as inversely proportional to “distance”; the standard law — and this chapter — is inverse-square (1/distance²). Papers that test it test the square.
• Momentum conservation, lecture shorthand vs standard: the lecture’s “clockwise = anticlockwise” phrasing belongs to moments in equilibrium; momentum conservation is total momentum before = total momentum after in an isolated system, and that is what this chapter teaches.
• Moon weight: mass does not change on the Moon — only weight does (0.166 × Earth). A “60 kg man weighs 10 kg on the Moon” question is testing weight, and the banks phrase it in kg as a weight unit.

14. Memory tricks (lectures first, then clean professional hooks)

• “Necessary evil”: friction’s own nickname — it resists motion, yet without it cars could not corner (centripetal force from friction) and we could not walk. Evil, but necessary.
• F = ma, KE = ½mv², PE = mgh, V = IR, v = fλ, τ = F × r: six formulas, each one letter-pair — learn them as a chant in this order (motion → energy → electricity → waves → turning).
• 7 bases in one line: Length-metre, Mass-kilogram, Time-second, Current-ampere, Temperature-kelvin, Substance-mole, Luminous-candela — “Let Me Take Care To Study Light” (initials L-M-T-C-T-S-L in table order).
• Red longest, violet shortest: the rainbow reads longest-to-shortest from the outside in — Red first, Violet last.
• Rectifier / inverter: Rectifier Routes AC into DC (both start with the same direction of conversion the name hides: AC→DC); Inverter Inverts it back.
• Motor / generator: a motor moves (electrical → mechanical); a generator generates electricity (mechanical → electrical). The verb is the conversion.
• SONAR in the sea, radar in the air: SONAR = Sound (water), Radar = Radio (air and space). The first letter picks the medium.
• 746 watts: one horsepower is roughly three-quarters of a kilowatt — 746 ≈ ¾ kW. The banks ask it both ways; “three-quarters” lands you on 746, not 7460.
• 7 miles = 11.2 km = 40,000 km/h: escape velocity’s three costumes — miles for the lecture, kilometres per second for the paper, kilometres per hour for the rocket question.
• Steel > rubber, honey > water: elasticity and viscosity run opposite on the same pair — steel wins elasticity, honey wins viscosity. One pair, two answers, no confusion if you name the property first.
• Silver conducts, silicon semiconducts: the two S-materials — silver is the best conductor, silicon the semiconductor and the solar cell. Same letter, opposite jobs.

15. Visuals (site build specs)

• INFOGRAPHIC — The 7 SI bases + derived units table: Section 2 rendered as a revision grid (quantity → unit → asked-as), with horsepower 746 W and decibel 30–60 dB called out — placed in Section 2.
• DIAGRAM — The conversion square: motor / generator / transformer / photovoltaic cell as a four-panel conversion diagram (electrical ↔ mechanical, voltage levels, solar → electricity) — placed in Section 7.
• DIAGRAM — Sound through media: one panel showing sound blocked by vacuum, slower in air, faster in water, fastest in steel, with the temperature arrow (hotter → faster) — placed in Section 5.
• INFOGRAPHIC — The lens pair: convex (thicker middle, magnifying glass, long sight, real inverted camera image) beside concave (thicker sides) — placed in Section 6.
• TIMELINE/DIAGRAM — The energy chain: dam water PE → mechanical → electrical beside the renewable/non-renewable split and the reactor (controlled) vs bomb (uncontrolled) pair — placed in Section 9.
• DIAGRAM — The formula strip: F = ma, KE = ½mv², PE = mgh, V = IR, v = fλ, τ = F × r as a single revision strip — placed in Section 10.

16. Practice this topic

• Practice set: 208 verified past-paper questions in the PPSC + FPSC banks are tagged to this topic’s sub-topics (units & measurements 27, light/sound/waves 68, motion/force/gravity 28, heat & thermodynamics 5, electricity & magnetism 24, nuclear & energy sources 56) — the site serves them as this chapter’s practice set, with the IBES Everyday Science capsule questions behind them. Note for the build: the practice set is filtered by the topic’s subject+topic tags at serve time, so the electric-current unit question serves both the units set and the electricity set by design, and Pakistan’s hydroelectricity questions serve both this chapter’s energy set and Chapter PS-13’s dams set.
• Book mode: ← Previous: Vitamins, Food & Nutrition · Next: Chemistry in Daily Life (Everyday Science) →

Goldmine Notes · Everyday Science · Chapter 6 · Sources: EDS Lecture 9 — Physics by Hammad Arshad (detailed notes, rechecked) for the lecture-taught definitions, formulas, units and values; verified PPSC/FPSC past-paper banks (208 topic questions, script-counted, hidden_files/goldmine-notes-count-eds06.py); IBES Everyday Science capsule bank behind the chapter; Pakistan nuclear-programme and hydroelectricity facts from the banks’ own keys (PAEC 1956, KANUPP Canada 1971/1972, Chashma China 325 MW grid 2000). Coverage-audit addition 2026-11-03 (PARR-I first-reactor row, Section 9 + rapid-fire + Section 13 trap): PMS Screening 2026 GK Mock 4 (Sir Adnan booklet, files/pms-papers/pms-2026-gk-mock-4.json) Q21, closing the Mock 1 held item (first reactor, Mock 1 Q10); script hidden_files/goldmine-notes-count-eds06-parr.py over 732 files / 70,189 questions — zero genuine PARR rows (all 11 ‘parr’ hits are sparrow/parrot/parry/Parramatta false positives), 1 bare ‘first nuclear reactor’ bank row keys KANUPP (taught as the trap above, not adopted as the reactor answer); no 🔁/⭐/🆕 claimed, bankCount 208 unchanged; PARR-I facts verified against standard references — IAEA INIS records (PARR-1, 5 MW pool-type, critical 1965, upgraded to 10 MW on LEU fuel 1991) and PNRA’s research-reactor record (PARR-1, 10 MW, 1965 vintage, US-supplied under Atoms for Peace) — plus the 21 December 1965 criticality date from the PINSTECH reactor history. Standard answers only.