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GCSE Physics Energy and Circuits
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GCSE Physics Energy and Circuits
GCSE Physics Energy and Circuits
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1
Question
What power of ten does the prefix tera represent in physics calculations?
Answer
\( \times 10^{12} \). Used for very large quantities in SI units.
2
Question
How do you convert milliamps to amps in physics calculations?
Answer
Multiply by \(10^{-3}\), since milli means \(\times 10^{-3}\). For example, 40 milliamps = 40 \(\times 10^{-3}\) amps.
3
Question
Why is the pattern in SI prefixes decreasing by powers of three useful for memorization?
Answer
It allows quick recall of orders of magnitude without listing all; notice gaps like centi to milli skip systematically by 3s.
4
Question
What is a closed system in the context of energy conservation?
Answer
A system where energy cannot escape or enter, so total energy remains constant but transfers between stores.
5
Question
How does kinetic energy store differ from gravitational potential energy store?
Answer
Kinetic is energy of moving objects (e.g., car); gravitational potential is energy from height above ground (e.g., book on shelf).
6
Question
What are the four methods of energy transfer between stores?
Answer
Heating (temperature gradient), radiation (waves like infrared), electrical work (charge flow), mechanical work (force over distance).
7
Question
Why does a falling book demonstrate mechanical energy transfer?
Answer
Gravitational potential energy converts to kinetic via gravity force over distance (mechanical work).
8
Question
What is the equation for kinetic energy, including units?
Answer
\( E_k = \frac{1}{2} m v^2 \), joules (J) for energy, kg for mass, m/s for velocity.
9
Question
How do you derive elastic potential energy equation from symbols?
Answer
\( E_e = \frac{1}{2} k e^2 \), where k is spring constant (N/m), e extension (m), energy in J.
10
Question
Why is gravitational field strength g in N/kg for GPE calculation?
Answer
GPE = m g h; g accelerates mass (force/mass = N/kg), energy J = kg * (N/kg) * m.
11
Question
What does specific heat capacity measure in thermal energy changes?
Answer
Energy to raise 1 kg of substance by 1°C; \(\Delta E = m c \Delta \theta\), c in J/kg°C.
12
Question
How does power relate to energy transfer rate?
Answer
Power = energy/time (P = E/t) or work/time (P = W/t); quicker transfer means higher power, W = J/s.
13
Question
According to conservation of energy, what happens to dissipated energy?
Answer
Transferred to less useful stores like thermal surroundings; cannot be created/destroyed, eventually all to thermal store.
14
Question
Why does higher thermal conductivity increase energy transfer rate?
Answer
Faster conduction through material; wax melts first on highest conductivity rod in experiment.
15
Question
How is energy efficiency calculated as percentage?
Answer
(useful output / total input) × 100, or same for power; increase by minimizing dissipated energy.
16
Question
What distinguishes renewable from non-renewable resources?
Answer
Renewable replenish as used (wind, solar); non-renewable finite, not replenished on human timescale (fossil fuels, nuclear).
17
Question
Why are fossil fuels considered non-renewable despite slow natural formation?
Answer
Formation takes millions years, not at rate of use; finite available now.
18
Question
Compare advantages of nuclear fission to fossil fuels?
Answer
Enough supply, reliable, no pollutant gases (CO2/SO2); but waste disposal issues vs. fossil spills.
19
Question
Why is solar power unreliable despite no pollutants?
Answer
Depends on sunlight; needs sunny conditions, unlike always-available tides.
20
Question
How does tidal power damage marine habitats?
Answer
Installation equipment disrupts ecosystems; reliable tides but uncontrollable supply by lunar cycle.
21
Question
What makes hydroelectric power controllable unlike wave?
Answer
Dams allow demand-based release; cheap run, but high initial cost/habitat loss.
22
Question
Why do wind turbines cause noise pollution?
Answer
Operation generates sound; weather-dependent supply, land use for scale.
23
Question
How are biofuels carbon neutral?
Answer
Plants absorb CO2 growing, release same combusting; reliable, controllable unlike geothermal.
24
Question
What circuit symbol represents a closed switch?
Answer
Two vertical lines connected horizontally, gap filled; open has gap.
25
Question
How does LDR symbol differ from thermistor?
Answer
LDR: rectangle with arrows toward (light); thermistor: rectangle with tick/diagonal line (temp).
26
Question
What equation links charge flow, current, and time?
Answer
\( Q = I t \), coulombs (C) = amps (A) × seconds (s).
27
Question
Why does higher resistance decrease current for fixed PD?
Answer
V = I R; harder flow like narrower pipe, less charge passes.
28
Question
Why does filament lamp show non-linear I-V graph?
Answer
Increasing current heats filament, atoms vibrate more, colliding electrons harder—increasing resistance.
29
Question
How to measure component resistance in circuit?
Answer
Ammeter series for I, voltmeter parallel for V; R = V/I.
30
Question
In series circuits, why is current same everywhere?
Answer
Single loop, charge conserves—no branching, like cars one path.