Electricity

Question 1

What is current measured in?

Answer 1

Amps (A)

Question 2

What is the equation for resistance?

Answer 2

Resistance= p.d÷ current

Question 3

What is resistance?

Answer 3

How hard it is for the current to flow

Question 4

List the three equations for power

Answer 4

Power= energy÷ time
Power= p.d× current
Power= current (squared)× resistance

Question 5

What is power?

Answer 5

Energy transferred per second

Question 6

Name the 3 cores, their colour and use.

Answer 6

•live core, brown, alternating p.d
• neutral, blue, completes circuit
•earth, yellow/green, safety

Question 7

What is potential difference?

Answer 7

Energy transferred per unit of charge

Question 8

What is potential difference measured in?

Answer 8

Ohms

Question 9

What are the energy stores?

Answer 9

Gravitational potential
Electrostatic
Thermal (internal)
Magnetic
Elastic potential
Nuclear
Chemical
Kinetic

Question 10

What is the national grid and how does it work?
How does it increase efficiency?

Answer 10

The national grid is transformers, cables and pylons.
Set up transformers increase p.d which lowers the current.
This increases efficiency as less energy is wasted by heat.

Question 11

What is a fuse?

Answer 11

A fuse is a safety device that protects the component.
If the current gets too high, the fuse line melts and snaps. This breaks the circuit, stopping the current.

Question 12

What is power measured in?

Answer 12

Watts

Question 13

What is resistance measured in?

Answer 13

Volts (v)

Question 14

What is the equation for current?

Answer 14

Current= charge÷ time

Question 15

What is current?

Answer 15

The rate of flow of charge

Question 16

Why do people get electric shocks?

Answer 16

•p.d between the live wire and the person, the person has zero volts.
•current will flow through the person to the ground
•the current becomes earthed

Question 17

What is the equation for potential difference?

Answer 17

P.d= energy÷ charge

Question 18

Name the energy pathways.

Answer 18

Radiation
Electrical work
Mechanical work
Heating

Question 19

What is work done measured in?

Answer 19

Joules

Question 20

What is the equation for work done?

Answer 20

Work done= force× distance

Question 21

What is gravitational potential energy measured in?

Answer 21

Joules

Question 22

What is kinetic energy measured in?

Answer 22

Joules

Question 23

What is the equation for kinetic energy?

Answer 23

Kinetic energy= 1/2× mass× velocity

Question 24

Elastic potential energy measured in?

Answer 24

Joules

Question 25

What is the equation for elastic potential energy?

Answer 25

Elastic potential energy= 1/2× spring constant× extension

Question 26

What is the equation for efficiency?

Answer 26

Efficiency= useful output energy÷ total input energy

Question 27

How is an electrical current produced?

Answer 27

An electrical current is produced by spinning a magnet next to a cool of wire. An alternating current will flow if the coil is connected in a circuit.

Question 28

What are the property's of a series circuit?

Answer 28

•current is the same everywhere •p.d is shared between the components

Question 29

What are the properties of parallel circuits?

Answer 29

•current is shared among the branches •p.d total on each branch is the same

Question 30

What is a short circuit?

Answer 30

A short circuit is when an electrical device develops a fault which results in the live wire touching the neutral wire.