Electricity and Energy Concepts

These flashcards cover key concepts from the lecture notes on electricity, energy resources, and energy transfer.

What does LDR stand for?

Light Dependent Resistor.

How does an LDR behave in bright light?

The resistance falls.

What happens to the resistance of an LDR at night?

The resistance increases.

Name one use of LDRs.

Outdoor night lights or burglar detectors.

What happens to all components in a series circuit if one component is broken?

All components will stop working.

What remains the same wherever the ammeter is placed in a series circuit?

The current reading.

What does AC stand for in electricity?

Alternating Current.

What is the frequency of the UK mains supply?

50 hertz (Hz).

What does DC stand for?

Direct Current.

What is the live wire's function in a circuit?

It provides the potential difference from the mains.

What does the neutral wire do?

Completes the circuit.

What happens to total resistance in a series circuit?

It adds up to make the total resistance.

What is a thermistor?

A temperature dependent resistor.

What happens to the resistance of a thermistor when it is hot?

The resistance is less.

What is the effect of adding resistors in series?

It increases the total resistance.

How is electric current defined?

The flow of electric charge.

What two units are charge measured in?

Coulombs (C).

How is charge calculated?

Charge flow (C) = current (A) × time (s).

What does potential difference measure?

The difference in electrical charge between two points.

What is the earth wire used for?

Protection; it carries a current if there is a fault.

What is the formula for energy transferred?

Energy (E) = power (P) × time (t).

What is the National Grid?

A system of cables and transformers transferring electrical power.

What do step-up transformers do?

Increase the voltage as electricity flows through the cables.

What do step-down transformers do?

Decrease the potential difference to make it safe.

What do renewable energy resources provide?

They will never run out.

What is one disadvantage of renewable energy resources?

They can be unreliable.

What does efficiency compare?

Useful output energy transfer to total input energy transfer.

What kind of power does a wind turbine use?

Wind energy.

What is the impact of non-renewable resources?

They will run out and damage the environment.

What is specific heat capacity?

The amount of energy needed to raise the temperature of 1kg of a material by 1°C.

What energy store is associated with moving objects?

Kinetic energy.

What happens when an object is stretched?

It gains elastic potential energy.

What is gravitational potential energy?

Energy stored when an object is raised above the ground.

What is the unit for power?

Watts (W).

How is power defined in relation to energy transfer?

The rate of transfer of energy.

What does an insulation do?

Reduces the amount of heat lost.

What is the method to calculate work done in terms of power?

Work done = power (W) × time (s).

What is the formula to calculate resistance?

Resistance (R) = voltage (V) / current (A).

What characterizes an ohmic conductor?

Current is directly proportional to potential difference.

What is the behavior of a diode in a circuit?

Current only flows in one direction.

What is the unit for energy?

Joules (J).

What is conservation of energy?

Energy can never be created or destroyed, only transferred.

How does conduction transfer energy?

By vibrating particles colliding in a solid.

What is convection in terms of energy transfer?

The movement of liquid or gas particles that become less dense when heated.

What happens to the electrons when materials are rubbed together?

Electrons can move from one material to another.

Define static electricity.

A build-up of charge caused by friction.

What will happen if a charged object is placed near an electric field?

It will experience a force.

What does energy efficiency mean in terms of energy wasted?

Less energy wasted means more efficient energy transfer.

What are the two equations to calculate efficiency?

Efficiency = useful output / total input or Efficiency = useful power output / total power input.