PHYSICS PAPER 1

What are the main energy stores?

Thermal, kinetic, gravitational potential, elastic potential, chemical, magnetic, electrostatic and nuclear.

What is the law of conservation of energy?

Energy cannot be created or destroyed. It can only be transferred between stores.

What is meant by a system?

An object or group of objects being considered.

What is the equation for kinetic energy?

Ek = ½mv²

• Ek = kinetic energy (J)

• m = mass (kg)

What is the equation for gravitational potential energy?

Ep = mgh

• Ep = gravitational potential energy (J)

• m = mass (kg)

• g = gravitational field strength (N/kg)

• h = height (m)

What is the equation for elastic potential energy?

Ee = ½ke²

• Ee = elastic potential energy (J)

• k = spring constant (N/m)

• e = extension (m)

What is work done?

Work done is the energy transferred when a force moves and object through

What is the equation for work done?

W = Fs

• W = work done (J)

• F = force (N)

• s = distance moved in the direction of the force (m)

What is power?

Power is the rate at which energy is transferred

What is the equation linking power, current and potential difference?

P = VI

What is efficiency?

The proportion of the input energy that is transferred usefully.

Efficiency = useful output energy ÷ total input energy × 100

What does it mean when energy is dissipated?

Energy is transferred into less useful stores, usually the thermal store of the surroundings.

What are renewable energy resources?

Resources that are naturally replenished, such as wind, solar, hydroelectric, tidal and geothermal energy.

What are non-renewable energy resources?

Fossil fuels and nuclear fuel. They are finite and will eventually run out.

Give advantages and disadvantages of fossil fuels.

They are reliable and can produce large amounts of energy, but burning them releases carbon dioxide and other pollutants.

Why does increasing the efficiency of a device reduce energy consumption?

More of the input energy is transferred usefully, so less energy needs to be supplied for the same useful output.

What is electric current?

The rate of flow of charge.

I = Q/t

• I = current (A)

• Q = charge (C)

• t = time (s)

What is potential difference?

he energy transferred per unit charge.

V = W/Q

What is resistance?

Resistance is how difficult it is for current to flow through a component.

R = V/I

What happens to current in a series circuit?

The current is the same everywhere in the circuit.

What happens to potential difference in a series circuit?

The potential differences across the components add up to the total potential difference supplied.

What happens to current in a parallel circuit?

The current splits between the branches. The total current equals the sum of the currents in the branches.

What happens to potential difference in parallel branches?

The potential difference is the same across each branch.

How does resistance change when resistors are added in series?

Total resistance increases.

How does adding another branch in parallel affect total resistance?

Total resistance decreases.

What is the equation for electrical power?Total resistance decreases.

P=VI
P = I²R
P = V²/R

What is the equation for energy transferred by an electrical device?

E = Pt
E = QV

What is the difference between a conductor and an insulator?

A conductor allows charge to flow easily. An insulator strongly resists the flow of charge.

What happens to the resistance of a metal wire as temperature increases?

Its resistance increases.

How does resistance change as the length of a wire increases?

Resistance increases.

How does resistance change as the cross-sectional area of a wire increases?

Resistance decreases.

What is the relationship between resistance, potential difference and current?

V = IR

A larger resistance gives a smaller current for the same potential difference.

What is the purpose of a fuse?

A fuse melts and breaks the circuit if the current becomes dangerously high.