Topic 2

Question 0

The voltmeter:

Answer 0

Measures the voltage or potential difference across the component

Must be placed in parallel around the component under test

Question 1

The ammeter:

Answer 1

Measures the current flowing through the component

Must be placed in series

Question 2

Current:

Answer 2

Rate of flow of charge round the circuit

Current will only flow through a component if there is a voltage across the component

Unit - A (amps)

Question 3

Voltage (potential difference):

Answer 3

The driving force that pushes the current round

Unit: V (volts)

Question 4

Resistance:

Answer 4

Anything in the circuit which slows the flow down

Unit: ohms

Question 5

If you increase the voltage:

Answer 5

Then more current will flow

Question 6

If you increase the resistance:

Answer 6

Then less current will flow

Question 7

What is potential difference:

Answer 7

The energy transferred per unit charge passed

Question 8

When is current conserved:

Answer 8

At a junction

Question 9

Parallel circuits:

Answer 9

Each component is separately connected to the +ve and -ve of the supply

There are junctions where the current either splits or rejoins

Current dosen’t get used up or lost in a circuit - it is conserved

Total current entering a junction is equal to the total current leaving a junction

Question 10

Word equation for potential difference:

Answer 10

Potential difference = current x resistance

Question 11

Fixed Resistor:

Answer 11

Current is directionally proportional to voltage

Graph is a straight line

Resistance is constant

Question 12

Filament lamp:

Answer 12

Current is not directly proportional to the voltage

Graph is not a straight line

Resistance is greater at higher voltages

Question 13

Diode:

Answer 13

Current only flows in one direction. Only flows when the voltage is above +0.6 V

Resistance is much greater in one direction than the other

Question 14

What is a light-dependant resistor (LDR):

Answer 14

Special type of resistor that changes it’s resistance depending on how much light there is

Question 15

What happens to the LDR in bright light:

Answer 15

The resistance falls

Question 16

What happens to the LDR in darkness:

Answer 16

Resistance is highest

Question 17

What is a Thermistor (temperature-dependant resistor):

Answer 17

Changes it’s resistance depending on the temperature

Question 18

What happens to the resistance in a thermistor in hot conditions:

Answer 18

The resistance drops

Question 19

What happens to the resistance in a thermistor in cool conditions:

Answer 19

Resistance goes up

Question 20

When do resistors get hot:

Answer 20

When an electric current passes through them

Question 21

What is electrical power:

Answer 21

The rate at which an appliance transfers energy

Question 22

What is power measured in:

Answer 22

Watts (W)

Question 23

What is the formula for electrical power:

Answer 23

Electrical power = potential difference x current

Question 24

What is the formula for energy transferred:

Answer 24

Energy transferred = current x potential difference x time

Question 25

What happens to an appliance with a high power rating:

Answer 25

Transfers a lot of energy in a short time

Question 26

Advantages of the heating effect of electrical current:

Answer 26

Kettles Electric blankets Seat warmers

Question 27

Disadvantages of the heating effect of electrical current:

Answer 27

Anything where heat energy is wasted If too much current flows, component can get to hot

Question 28

What is energy measure in:

Answer 28

Joules

Question 29

What is charge measured in:

Answer 29

Coulombs