Energy, Electricity, and Radioactivity: Key Concepts and Formulas

What is energy?

The ability to do work or cause change.

What is the law of conservation of energy?

Energy cannot be created or destroyed, only transferred or stored.

What is gravitational potential energy?

Energy stored due to height above the ground.

What is the equation for gravitational potential energy?

GPE = mgh

What happens in an energy transfer?

Energy moves between stores or objects.

What is useful energy?

Energy transferred in the way you want.

What is wasted energy usually transferred as?

Heat (thermal energy).

What is power?

The rate of energy transfer.

What is the equation for power?

Power = Energy ÷ Time

What is the unit of power?

Watt (W)

Name two renewable energy resources.

Solar, wind, hydro (others acceptable).

Name two non-renewable energy resources.

Coal, oil, gas, nuclear.

What is current?

Flow of electric charge.

What is the unit of current?

Ampere (A)

What is the charge equation?

Q = It

What is potential difference?

Energy transferred per unit charge.

What is the unit of potential difference?

Volt (V)

What is Ohm's Law?

V = IR

What does resistance measure?

How much a component opposes current.

What happens to resistance when temperature increases (metal wire)?

Resistance increases.

What is the current in series circuits?

Same everywhere.

What is the current in parallel circuits?

Splits between branches.

What is the voltage in parallel circuits?

Same across each branch.

What is the UK mains voltage?

About 230 V.

What does a fuse do?

Melts to break the circuit if current is too high.

Why are earth wires used?

Prevent electric shock.

What is the density equation?

Density = mass ÷ volume

What is the unit of density?

kg/m³

What happens during melting?

Solid → liquid.

What happens during boiling?

Liquid → gas.

Does temperature change during state change?

No — energy breaks bonds.

What happens to gas pressure when temperature increases?

Pressure increases (if volume constant).

Why does gas pressure increase with temperature?

Particles move faster and hit container walls more.

What is an isotope?

Same element, different number of neutrons.

Where are electrons found?

In shells around the nucleus.

Which radiation is most ionising?

Alpha.

Which radiation is most penetrating?

Gamma.

What is contamination?

Radioactive material getting onto or into something.

What is irradiation?

Exposure to radiation only (no material transferred).