DC and AC Supply

Question 1

the current(conventional) leaves from which side to which side?
what symbol represents this flow?

Answer 1

from positive end of the cell to negative end of the cell

a conventional arrow =

Question 2

the current from a cell is a direct current (DC)

what does this mean?

Answer 2

it moves in only one direction
(leaves from one end, makes its way around the circuit and leaves through the other end
(the electrons only ever travel in one direction)

Question 3

what is mains electricity in the UK

Answer 3

an alternating current
an (AC)

it is NOT a direct current

Question 4

what does an alternating current mean?

Answer 4

the current is constantly changing direction

Question 5

what is the benefit of using an alternating current?

Answer 5

benefit of AC:

very easy to use a transformer to increase or decrease the pd

Question 6

what is the AC frequency in the UK

Answer 6

50Hz

In the UK, alternating current has a frequency of 50Hertz (Hz)

Question 7

what’s the potential difference of the AC in the UK

Answer 7

around 230V

the AC in the UK has a pd of around 230 volts

Question 8

in the UK the alternating current switches direction 50x a second what do we scientists say to express this?

Answer 8

it has a frequency of 50hertz (Hz)

what do

Question 9

how can scientists see the pattern of an electrical current ?

Answer 9

using a machine called oscilloscope

Question 10

what is an oscilloscope

Answer 10

a machine that tells us the pattern of an electrical current

Question 11

what does the oscilloscope show?

Answer 11

shows an alternating current, the pd rises and falls
this shows that the current has gone backwards and forwards

can also be used to show us the direct current

Question 12

what does the height of the peak tell us in an oscilloscope?

Answer 12

the maximum potential difference

Question 13

how would the direct current look like on an oscilloscope

Answer 13

the pd does not change, stays in a straight line

Question 14

what can we use the oscilloscope for in an AC?

how do we do this?

Answer 14

to calculate the FREQUENCY of and alternating current

Question 15

In a graph there is a peak at 0.01 sec and the next one is at 0.03sec
how long did it take/ what is the time interval for the alternating current to switch ?

what is the frequency?

Answer 15

0. 02s
1. 03s-0.01s

frequency = 50Hz

frequency= number of cycles in 1 second
we know that each cycle takes 0.02s so to find out how many in 1 we do
frequency (Hz)= 1/0.02
frequency = 50Hz