Electricity

Question 1

Define current

Answer 1

Rate of flow of charge round the circuit

Electrons carry charge (negatively charged)

Current only flows through a component if there is a voltage across that component

Question 2

What is current measured in?

Answer 2

Amperes (amps) , A

Question 3

Define voltage

Answer 3

Drives the current round the circuit.

Also called potential difference

Question 4

Voltage measured in

Answer 4

Volts, V

Question 5

Define charge

Answer 5

Electrical energy and is being carried around by electrons

Question 6

Resistance define

Answer 6

Anything in the circuit which slows the flow down

The more components the higher the overall resistance

Question 7

Resistance measured in

Answer 7

Ohms,

Question 8

If increase the voltage

Answer 8

More current will flow

Question 9

If increase resistance

Answer 9

Less current will flow

Question 10

Which way does a circuit flow?

Answer 10

Negative to positive electrical flow

Opposites attract

Question 11

Circuit symbols 
Cell
Battery
Power supply
Switch open and closed
Earth / ground
Filament lamp
LED
Loudspeaker + microphone 
Electrical bell + motor
Fixed resistor + variable resistor
Ammeter + voltmeter
Diode 
LDR
Heater + generator
Fuse / circuit breaker
Thermistor
Transformer 
Relay

Answer 11

Question 12

Difference between cell and battery

Answer 12

Cell = simpler
Battery = complex - more layers (of cells)

Question 13

Ammeter
Define
Where to place

Answer 13

Measures current (amps) flowing through the component

Must be placed in series
Anywhere in the main circuit but never in parallel

Question 14

Voltmeter
Define
Where to place

Answer 14

Measures voltage (volts) across the component

Must be placed in parallel

Question 15

Where to place variable resistor

Answer 15

Series

Question 16

What happens

Alter the resistance of variable resistor

Answer 16

Current flowing through the component changes

Question 17

Mains supply is …

Battery supply is …

Answer 17

a. c.

d. c.

Question 18

UK mains electricity supply is ….

a. c. Stands for …..
a. c. Means …..
d. c. stands for ….
d. c. means …

Answer 18

230 Volts

Alternating current

Current is constantly changing direction

Direct current

Current keeps flowing in same direction

Question 19

Formula
Voltage
Current
Resistance

Answer 19

Voltage (V) = current (A) x resistance (ohms)

V
I x R

Question 20

I - V graphs (current - voltage)
What they show
For straight line…
If curves…..

Answer 20

Changing voltage affect current

For a straight line graph the gradient is constant and equal to:
1 / resistance (bc. R = V / I)

Curves: resistance is changing

Question 21

Formula

Work out resistance from I-V graph

Answer 21

R = V / I

Question 22

List 4 important current - voltage graphs

Answer 22

Metal filament lamp
Wire
Different resistors
Diode

Question 23

Describe
I - V graph
Metal filament lamp

Answer 23

As temperature of metal increase the resistance increases hence the curve

Question 24

Describe
I - V graph
Wire

Answer 24

The current through a wire (at constant temperature ) is proportional to voltage

Question 25

Describe I-V graph Different resistors

Answer 25

Current through resistor (at constant temperature) is proportional to voltage Different resistors have different resistances Hence different slopes

Question 26

Describe I-V graph Diode

Answer 26

Current will only flow through a diode in one direction as shown

Question 27

LED stand for

Answer 27

Light Emitting Diode

Question 28

LEDS emit light when

Answer 28

Current flow through them in the forward direction

Question 29

LEDs are used for

Answer 29

Numbers on digital clocks Traffic lights Remote controls

Question 30

Unlike a light bulb LEDs ….

Answer 30

Don’t have a filament that can burn out

Question 31

What is a LDR and stand for

Answer 31

Light dependent resistor Type of resistor Changes resistance depending on how much light falls on it

Question 32

LDRs in bright light and darkness

Answer 32

Bright: resistance falls Dark: resistance is highest

Question 33

LDRs used for

Answer 33

Electronically circuits eg burglar detectors

Question 34

LDR graph looks like

Answer 34

Question 35

What is thermistor

Answer 35

Temperature dependent resistor

Question 36

Thermistor in hot and cool conditions

Answer 36

Hot: resistance drops Cool: resistance goes up

Question 37

Thermistors used for

Answer 37

Temperature detectors Eg car engine temperature sensors Thermostats Fire alarms

Question 38

Thermistor graph looks like

Answer 38

Question 39

What happens | Remove a component in series circuit

Answer 39

Circuit stops working

Question 40

Series circuit uses

Answer 40

Fairy lights and Christmas tree lights

Question 41

In parallel circuit | Remove a component

Answer 41

Still works

Question 42

``` Parallel circuits Potential difference Current Junctions Current / resistance Total resistance ```

Answer 42

Question 43

Charge (circuit depends on)

Answer 43

Current and time

Question 44

Charge Current Time Equation

Answer 44

Charge = current x time Q I. X. T

Question 45

The more charge passes around a circuit when a ….

Answer 45

Bigger current flows

Question 46

When a charge drops through a voltage it…

Answer 46

Transfers energy

Question 47

Equation Energy transferred Charge Voltage

Answer 47

Energy transferred = charge x voltage

Question 48

``` Equation Energy transferred Charge Current Resistance ```

Answer 48

Energy transferred = charge x current x resistance

Question 49

Earthing and fuses prevent ….

Answer 49

Fires and shocks

Question 50

Wires Blue = Green / yellow = Brown =

Answer 50

Neutral wire Earth Live

Question 51

Electrical safety

Answer 51

Question 52

Resistors when current passes through

Answer 52

Get hot

Question 53

Equation Electrical power Current Voltage

Answer 53

Question 54

``` Formula Energy transferred Current Voltage Time ```

Answer 54

Energy transferred = current x voltage x time

Question 55

Repel = | Attract =

Answer 55

Like charges (same) Opposite

Question 56

Attraction Repulsion Repulsion

Answer 56

Question 57

Conductors … | Insulators…

Answer 57

Conduct charge | Don’t conduct charge

Question 58

Static charge … move

Answer 58

Can not

Question 59

What is static charge?

Answer 59

Question 60

As charge builds up so does the voltage Experiments can show the effects of static electricity

Answer 60

Question 61

Give and explain 3 experiments to check a material / investigate charge

Answer 61

Question 62

How is static electricity used

Answer 62

Printer | Photocopier

Question 63

Explain static electricity in printer and photocopier

Answer 63

Question 64

Static electricity | Unhelpful

Answer 64

Clothing crackles Lightening Fuel