Physics Electricity Jan 2018

Question 1

What is resistance?

Answer 1

Resistance is how difficult it is for electrons/current to flow

Question 2

What happens when there is a low resistance?

Answer 2

There is a greater flow of current

Question 3

What equation do you use for Resistance?

Answer 3

V = I/R

Question 4

What is Voltage?

Answer 4

Voltage is the energy per unit charge(think of it as the energy carried by the electrons)

Question 5

What is current?

Answer 5

Current is the rate of flow of charge

Question 6

What happens to the voltage and current in a series circuit?

Answer 6

The voltages add up and the current stays the same

Question 7

What happens to the voltage and current in a parallel circuit?

Answer 7

The voltage is the same and the current adds up(remember traffic)

Question 8

The resistance of a wire is directly proportional to the ……. of the wire

Answer 8

Length

Question 9

The resistance of a wire is inversely proportional to the ……. of a wire

Answer 9

Thickness

Question 10

What is the equation used for current / charge?

Answer 10

I = Q / t or Q = It

Question 11

What is the unit for charge?

Answer 11

Coulombs

Question 12

What is the equation for voltage?

Answer 12

V = (W or E) / Q

Question 13

What are the 3 wires in a plug?

Answer 13

The earth, neutral and live.

Question 14

What is the purpose of the earth wire?

Answer 14

To carry charge away from the applicance to the ground when an accident occurs. Acts as as safety measure.

Question 15

What is the purpose of the neutral wire?

Answer 15

To carry charge away from the appliance and complete the circuit.

Question 16

What is the purpose of the live wire?

Answer 16

The live wire carries the 230 V charge towards the appliance but can be dangerous when not attached properly. (Hence why the earth wire is needed)

Question 17

What is the purpose of the fuse?

Answer 17

To blow the circuit when a certain amplitude is reached. This is a safety measure so that the appliance doesn’t become dangerous.

Question 18

What type of appliances need double insulation? Why?

Answer 18

Plastic appliances need two core cables because there is no earth wire.

Question 19

What is the definition of frequency?

Answer 19

The amount of cycles per second

Question 20

What is the definition of time period?

Answer 20

The time taken to complete 1 full cycle

Question 21

What is the equation for frequency?

Answer 21

f = 1/T

Question 22

What is the equation for time period?

Answer 22

T = 1/f

Question 23

What does ‘AC’ stand for? what is it?

Answer 23

‘AC’ stands for alternating current and is a type of electrical current in which the flow of current changes from one direction to the other.

Question 24

What is the mains supply?

Answer 24

The mains supply is the general-purpose alternating-current (AC) electric power supply

Question 25

What does 'DC' stand for? what is it?

Answer 25

'DC' stands for direct current and is a type of electrical current in which the flow of current always flows in the same direction.

Question 26

What is Ohm's Law?

Answer 26

Ohm's Law is the current is directly proportional to the voltage at a constant temperature.

Question 27

What happens when there is a high resistance?

Answer 27

There is a smaller flow of current

Question 28

What do field lines show us?

Answer 28

The direction of the field (e.g. from positive to negative) and the strength of the field

Question 29

What are field lines used for?

Answer 29

To represent an electric field.

Question 30

What is the definition of an electric field?

Answer 30

An electric field is a region in which charges (positive or negative) feel a charge.