Energy types
Name 4 different types of energy
Any of: kinetic, thermal, light, sound, electrical, chemical, gravitational potential, elastic potential, nuclear.
Give 5 examples of renewable energy sources.
Any 5 of: solar, wind, geothermal, hydroelectric, tidal, biomass, biogas.
What are the 4 key components of a basic electric circuit?
Conductive path, source of electrical power, load, switch.
What do the star ratings on electrical appliances indicate?
They show how energy-efficient an appliance is. More stars = more efficient = less energy used for the same output.
Why is global energy demand increasing?
Growing world population, industrialisation in developing countries, increased use of technology and transport.
What is the law of conservation of energy?
Energy cannot be created or destroyed — it can only be transferred or transformed. The total energy stays the same.
Give 3 examples of non-renewable energy sources.
coal, crude oil, natural gas, nuclear
What is voltage and what unit is it measured in?
Voltage (potential difference) is the 'push' that drives current around a circuit. Measured in volts (V).
What is the formula for energy efficiency?
Efficiency (%) = (useful energy output ÷ total energy input) × 100.
What is a fuel cell and what does it produce?
A fuel cell converts chemical energy (often from hydrogen) directly into electrical energy. The by-product is water.
What is the unit of energy?
Joule (J)
How does a coal-fired power station produce electrical energy?
Coal is burned → heats water → steam spins a turbine → turbine drives a generator → electricity is produced.
What is the difference between a series circuit and a parallel circuit?
Series: components in one loop, same current, shared voltage. Parallel: components in separate branches, same voltage, current splits.
Name 2 ways to improve energy efficiency in a home.
Any 2: better insulation, LED lighting, energy-efficient appliances, solar panels, draught-proofing, double glazing.
What does 'sustainable energy' mean?
Energy from sources that meet current needs without compromising the ability of future generations to meet their own needs.
A light globe is 20% efficient. It receives 500 J of electrical energy. How much light energy does it produce?
100J
Give one advantage AND one disadvantage of solar energy.
Advantage: renewable/free/no emissions. Disadvantage: only works during daylight, initial cost can be high, depends on weather.
State Ohm's law as a formula and name all three quantities and their units.
V = IR. Voltage (V) in volts, current (I) in amps, resistance (R) in ohms (Ω).
A heater is 75% efficient and receives 800 J of energy. How much useful heat energy does it produce?
75% of 800 J = 600 J.
Name 2 advantages of electric vehicles (EVs) over petrol vehicles.
Any 2: zero tailpipe emissions, more energy-efficient, lower running costs, reduced noise pollution.
A car engine transfers 2000 J but only 600 J becomes kinetic energy. What is its efficiency?
30%
Why might a government choose to invest in wind energy rather than coal?
Wind is renewable, produces no greenhouse gas emissions during operation, and does not run out. Coal is finite and produces CO₂, contributing to climate change.
A circuit has a voltage of 12 V and a resistance of 4 Ω. What is the current?
I = V ÷ R = 12 ÷ 4 = 3 A.
What is a by-product of most energy transformations, and why is it a problem for efficiency?
Thermal (heat) energy is produced as a by-product. It is 'wasted' energy, reducing useful output and lowering efficiency.
A country relies on coal for 80% of its electricity. Should it transition to renewables? Give one reason for and one against.
For: reduces greenhouse gas emissions/renewable/won't run out. Against: high transition cost, job losses in coal industry, reliability concerns.