the rate of energy transfer or the amount of energy transferred per second
New cards
5
what is power dependent on
voltage and current
New cards
6
relationship between power, current and voltage
power = current x voltage
New cards
7
unit of power
watts
New cards
8
fuse
a safety device that cuts off the flow of electricity to an appliance if the current becomes too large
New cards
9
what do the ratings on a fuse tell us
how much current it can withstand
New cards
10
what does exceeding the current rating on a fuse cause
the fuse blows
New cards
11
should the fuse have a current rating higher than the current needed
yes
New cards
12
what will a low fuse current rating do
it will break the circuit even when an acceptable current is flowing through
New cards
13
what will a too high fuse current rating do
it will not be breaking the circuit in enough time before damage occurs
New cards
14
insulation
wires are covered with an insulating material as the conducting part of the wire is usually made of a metal that poses a risk of electrocution
New cards
15
double insulation
appliances with two layers of insulation
New cards
16
two layers of insulation in double insulated wires
insulation around the wires
a non-metallic cased
New cards
17
do double insulated appliances require an earth wire
no because the earth wire can't touch the metal casing
New cards
18
earthing
many electrical appliances have metal cases which poses a potential safety hazard if the live wire comes into contact with the case risking electrocution
New cards
19
how does the earth wire protects the user
the earth wire provides a low resistance path to the earth causing a surge of current causing the fuse to melt and break which cuts off electricity supply to the appliance
New cards
20
circuit breaker
an electromagnet switch that breaks the circuit if the current exceedds a certain value h
New cards
21
how does a circuit breaker work
it quickly shuts off electricity to the whole house
New cards
22
how is a circuit breaker better than a fuse
it doesn't melt and break and works much faster
New cards
23
DC
direct current
New cards
24
how does DC current travel
in one direction only
New cards
25
does a DC power supply have a fixed terminal
yes
New cards
26
AC
alternating current
New cards
27
how does AC current travel
it constantly changes direction
New cards
28
does an AC power supply have a fixed terminal
it has 2 identical terminals that switch between positive and negative
New cards
29
frequency of an alternating current
number of times the current changes direction back and forth each second
New cards
30
where is DC current produced/used
cells and batteries
New cards
31
where is AC current produced/used
electrical generators
New cards
32
when is work done
when charge flows through a circuit
New cards
33
relationship between work done and energy transferred
work done = energy transferred
New cards
34
relationship between energy transferred, current, voltage and time
energy transferred = current × voltage × time
New cards
35
why does temperature increase when electricity passes through a component
it's turned into heat
New cards
36
what is energy a transfer of
collisions between electrons flowing in the conductor and lattice of atoms within the metal conductor
New cards
37
current
flow of electrons
New cards
38
atomic configuration of metals
lattice of metals
New cards
39
what happens to electrons as they flow through metals
they collide with ions which resist the flow of electronsh
New cards
40
how does metal heat up
electrons collide and lose energy by giving it to ions which vibrate more
New cards
41
which appliances can the heating effect be utilised in
Studied by 6 people
Note 
Flashcard (29)