electricity

Question 1

define current

Answer 1

a measure of the flow of electrons around a circuit

Question 2

what is potential difference?

Answer 2

the force driving the flow of electrons

Question 3

what is resistance?

Answer 3

anything that opposes the flow of electrons

Question 4

what is the function of diodes?

Answer 4

they only allow current to flow 1 way around a circuit

Question 5

what is charge?

Answer 5

a measure of the total current that flowed within a certain period of time

Question 6

what do ammeter and voltmeters measure?

Answer 6

ammeters- current
voltmeters- potential difference

Question 7

what do step up and step down transformers do?

Answer 7

step up- increase the voltage, decrease the current
step down- decrease the voltage, increase the current

Question 8

why does the national grid not use a high current? (instead a high voltage)

Answer 8

as high current generates lots of wasted energy
e.g heat

Question 9

what is the difference between AC and DC?

Answer 9

AC- the charge alternates its direction of travel
DC- the charge is always flowing in the same direction

Question 10

how is alternating current formed?

Answer 10

by an alternating potential difference

Question 11

what is the role of an oscilloscope?

Answer 11

display how voltage changes with time

Question 12

what does the live wire do?(brown)

Answer 12

supply the alternating potential difference
(supplies the current to the appliance)

Question 13

what does the neutral wire do? (blue)

Answer 13

completes the circuit by carrying away current

Question 14

what is the role of the earth wire? (yellow and green)

Answer 14

to stop the appliances casing from becoming live

Question 15

what is the role of fuses and circuit breakers?

Answer 15

to break the circuit when the current gets too high

Question 16

what is static electricity?

Answer 16

the build up of charge on an insulating object

Question 17

what happens if the potential differnce between a charged object and the earth is too high?

Answer 17

the electrons from the charged object can jump through the air onto earth in the form of a spark

Question 18

in which way do electric fields travel?

Answer 18

from positive to negative

Question 19

how does a fixed resistor graph look?

Answer 19

directionally proportional

Question 20

what will happen to resistance in wires when current is increased?

Answer 20

resistance will increase

Question 21

how does the graph for a flimaent lamp look?

Answer 21

__/
/

Question 22

how does a diode graph look?

Answer 22

single straight line on the positive corner (__/_)

Question 23

how are ammeters added to circuits ?

Answer 23

in series

Question 24

how are voltmeters added to circuits?

Answer 24

in parallel

Question 25

what is a thermistor?

Answer 25

a resistor whos resistance decreased when temperature increases

Question 26

in a series circuit how is p.d distributed?

Answer 26

shared across all components

Question 27

in a series circuit, how is current distributed?

Answer 27

the same everywhere in the circuit

Question 28

in parallel circuits, how is p.d shared?

Answer 28

same across all components

Question 29

how is current shared in a parallel circuit?

Answer 29

it is shared between all parallel loops

Question 30

what will happen to a circuit (with a resistor) when another resistor is added?

Answer 30

resistance will decrease

Question 31

what is the voltage of the neutral wire

Answer 31

0 volts

Question 32

what is double insulation while referring to an appliance?

Answer 32

just having plastic casing and no fuse