Static and Current electricty

Question 1

Where charges come from

Answer 1

Rubbing materials does not create electric charges. It just transfers electrons from one material to the other.

Question 2

Example of electric charges transferring

Answer 2

When a balloon rubs a piece of wool..

Electrons are pulled from the wool to the balloon.
The balloon has mor electrons than usual.

Balloon: negative charged
Wool: positive charge

Question 3

Static electricity

Answer 3

A stationary electrical charge that is built up on the surface of a material.

Question 4

insulator

Answer 4

material through which charge cannot flow

Question 5

conductor

Answer 5

material through which charge can flow

Question 6

electricity

Answer 6

electrons moving through a metal wire/circuit

Question 7

current

Answer 7

movement of electrons

Question 8

current measurement, symbol, how to measure

Answer 8

measurement: amps (A)
symbol: I

Measured using: ammeter

Question 9

voltage

Answer 9

measure of push or force that a power supply has to drive a current

Question 10

voltage measurement, symbol, how its measured

Answer 10

measurement - volts (V)

symbol - V

Measured using - voltmeter

Question 11

resistance

Answer 11

ability of a substance to reduce current

Question 12

resistance measurement, shmbol, measured using..

Answer 12

measured in: ohms (horseshoe symbol)

symbol: R

measured using: ohmmeter

Question 13

average voltage in Ireland

Answer 13

230 volts

Question 14

OHMS LAW diagram

Answer 14

diagram in hardback

Question 15

ohms law

Answer 15

Voltage is directly proportional to current

Question 16

direct current

Answer 16

pushes current in one direction only

eg. battery

Question 17

alternating current

Answer 17

current which is consistently changing direction

eg. current from ESB

Question 18

Why 2 LEDs would glow dimly if the battery was alternating current

Answer 18

current will only flow in current direction half the time, so LEDs will be dimmer

Question 19

OHMs law triangle

Answer 19

Current (i) x Resistance (R)

Question 20

two bulbs in series

Answer 20

If you remove one bulb, the other will not light,

Eg. christmas lights

Question 21

two bulbs in parallel

Answer 21

if you remove one bulb, the other will stay lighting

eg. bulbs in your house, car lights

Question 22

unit of electrical energy

Answer 22

kilowatt hour

Question 23

kilowatt hour

Answer 23

energy used when 1 kilowatt of power is used for 1 hour

Question 24

calculating cost of electrical appliances

Answer 24

no. of kilowatts x no. of hours = kilowatt hours

kilowatt hours x cost per unit = cost

Question 25

wats to kilowatts

Answer 25

kilowatts = watts / 1000

watts = kilowatts x 1000

Question 26

3 effects of electricity

Answer 26

heating effect,
chemical effect,
magnetic effect

Question 27

everyday uses of heating effect

Answer 27

boil water in a kettle
immersion heater
electric cooker

Question 28

fuse

Answer 28

a safety device

Question 29

fuse purpose

Answer 29

limit size of current flowing in circuit

Question 30

how a fuse works

Answer 30

when current flowing through plug is greater than current rating on fuse (eg. 13A) wire in fuse heats up + melts

breaks electric circuit, stops current flowing

Question 31

everyday uses of chemical effect

Answer 31

electroplating

recharge battery (eg. mobile phone)

Question 32

electroplating

Answer 32

expensive metal like silver is coated onto a less expensive metal

Question 33

magnetic use everyday uses

Answer 33

electromagnet

circuit breaker

Question 34

live wire

Answer 34

brown, on right

Question 35

neutral wire

Answer 35

blue, on left

Question 36

earth wire

Answer 36

yellow + green, middle

Question 37

diodes and batteries

Answer 37

in hardback

Question 38

forward bias

Answer 38

current flows.

eg
+ end of diode is connected to + terminal of battery

Question 39

reverse bias

Answer 39

current does not flow.

eg
- end of diode is connected to + terminal of battery

Question 40

what does LED stand for?

Answer 40

Light Emitting Diode

Question 41

why LEDs are more efficient

Answer 41

require less current, less energy is lost as heat

Question 42

LEDs

Answer 42

give out light when current flows through them

only emit light if it is in forward bias

resistor must be connected in series to limit current (too much burns out/damages LED)

Question 43

everyday applications of LEDs

Answer 43

Red light on electrical appliances - standby mode light on TV

Cyclists use LED lights

Question 44

LDR - what does it stand for

Answer 44

Light Dependent Resistor

Question 45

LDRS

Answer 45

resistor whose value of resistance can change as the intesnity of the light falling on it changes

Question 46

LDRS - bright light

Answer 46

resistance low

large current flows

Question 47

LDRs - dim light

Answer 47

resistance high

small current is flowing

Question 48

everyday applications of LDRs

Answer 48

light meter on camera - amount of light entering camera controls resistance of LDR, changes setting of camera

street lights
-darkness - resistance of LDR imcreases, actives control circuit to switch on light

Question 49

measure resistance of LDR with varying degrees of brightness

Answer 49

diagram in hardback,

result: value of resistance increased as brightness of bulb decreased.