Section 6: Electricity

Question 1

What is current?

Answer 1

Current is the rate of flow of charge.

Question 2

How is charge carried in a circuit?

Answer 2

Through the wires by electrons

Question 3

How do you work out current?

Answer 3

I = delta Q / delta t
Current = charge / time taken
Amps = Coulomb / seconds

Question 4

What is one coulomb defined as?

Answer 4

The amount of charge that passes in 1 second when the current is 1 ampere.

Question 5

How can you measure the current flowing through a circuit?

Answer 5

With an ammeter connected in series

Question 6

What do you need to make an electric charge pass through a circuit?

Answer 6

You need to transfer energy to the charge. This is supplied by the power source (e.g. A battery)

Question 7

What happens when a charge flows through a power source?

Answer 7

It’s raised through a potential and energy is transferred to the charge as electrical potential energy

Question 8

What happens when energy is transferred?

Answer 8

Work is done. The power source does work to move the charge around the circuit.

Question 9

What is potential difference?

Answer 9

It’s defined as the work done in moving a unit charge between the points (voltage)

Question 10

How can you work out potential difference (voltage)?

Answer 10

V = W / Q
Potential difference = work done / charge
Volts = joules / coulombs

Question 11

What is 1 volt also equal to?

Answer 11

1 volt = 1 joule of energy moving 1 coulomb of charge through the component

1 V = 1 JC^-1

Question 12

How can you measure the potential difference across an electrical component?

Answer 12

By using a voltmeter attached in parallel

Question 13

What is resistance?

Answer 13

A measure of how difficult it is to get a current to flow.

Question 14

What is resistance measured in?

Answer 14

Ohms

Question 15

When does a components have a resistance of 1 ohm?

Answer 15

If a potential difference of 1 volt makes a current of 1 amp flow through it

Question 16

What’s the equation to work out resistance?

Answer 16

R = V / I 
Resistance = voltage / current
Ohms = volts / amps

Question 17

What is ohms law?

Answer 17

It states that provided the physical conditions, such as temperature, remain constant, the current through an ohmic conductor is directly proportional to the potential difference across it

Question 18

What are ohmic conductors?

Answer 18

Materials that obey Ohms law (mostly metals)

Question 19

How can you write ohms law?

Answer 19

I is directly proportional to V

Question 20

What is the resistance like in ohmic conductors?

Answer 20

Constant (gradient of a IV graph)