electricity

Question 1

what is a battery?

Answer 1

more than 1 cell

Question 2

how must an ammeter be placed in a circuit?

Answer 2

in series

Question 3

how must a voltmeter be placed in a ciruit?

Answer 3

in parallel to the component

Question 4

what is needed for charge to flow through a closed circuit?

Answer 4

a source of potential difference, eg a cell

Question 5

define current

Answer 5

rate of flow of electrical charge

Question 6

what is the equation linking charge, current and time?

Answer 6

charge = current x time
(CHCT)

Question 7

define potential difference

Answer 7

the work done when a coulomb of charge passes between two points

Question 8

what is the equation linking potential difference, current and resistance?

Answer 8

potential = current x resistance
(PDCR)

Question 9

what is a series circuit?

Answer 9

the components are in 1 complete loop

Question 10

what is a parallel circuit?

Answer 10

the components are in more than 1 loop

Question 11

draw the current-potential difference graph for an ohmic conductor

Answer 11

/

Question 12

draw the current-potential difference graph for a filament lamp

Answer 12

. _
_/ (S shaped)

Question 13

draw the current-potential difference graph for a diode

Answer 13

___/

Question 14

how does the resistance of a thermistor change as temperature changes?

Answer 14

an increase in temperature decreases the resistance

Question 15

how does the resistance of an LDR change as light intensity changes

Answer 15

an increase in light intensity decreases the resistance

Question 16

how does current behave in a series circuit?

Answer 16

same at every point in a circuit

Question 17

how does pd behave in a series circuit

Answer 17

total pd of the power supply is shared between components

Question 18

how does resistance behave in a series ciruit

Answer 18

increases with number of components

Question 19

how do you calculate the total resistance of components in series

Answer 19

add the individual resistances together
Rtotal = R1 + R2

Question 20

how does current behave in a parallel circuit

Answer 20

current splits to go down different branches, and joins to go back through the power supply

Question 21

how does pd behave in a parallel circuit

Answer 21

pd across each branch is the same as the power supply

Question 22

how does resistance behave in a parallel circuit

Answer 22

total resistance of 2 resistors is less than the resistance of the smallest individual resistor

Question 23

how can you measure the resistance of a component

Answer 23

use an ammeter in series and a voltmeter in parallel to measure the pd across and the current through a component

Question 24

what is the pd of main electricity in the UK

Answer 24

230V

Question 25

what is the frequency of main electricity in the UK

Answer 25

50Hz

Question 26

what is direct current

Answer 26

the flow of charge is in one direction only

Question 27

what is alternating current

Answer 27

the flow of charge is continually changing direction

Question 28

what is direct pd

Answer 28

the pd is in one direction only

Question 29

what is alternating pd

Answer 29

the pd is continually changing direction

Question 30

what are the 3 wires in a plug

Answer 30

• live (brown)
• neutral (blue)
• earth (green and yellow stripes)

Question 31

what are the safety features on a plug

Answer 31

earth wire, fuse

Question 32

equation linking power, current and pd

Answer 32

power = pd x current
(PPDC)

Question 33

equation linking power, current, resistance

Answer 33

power = current x resistance
(PCR)

Question 34

what is power

Answer 34

the rate of energy transfer

Question 35

equation linking energy, power, time

Answer 35

power = energy divided by time
(PE/T)

Question 36

equation linking energy, charge, pd

Answer 36

energy transferred = charge flow x pd
(ETCFPD)

Question 37

what is the national grid

Answer 37

a system of cables and transformers ljnking power stations to consumers

Question 38

what does a step up transformer do

Answer 38

used to increase the pd from the power station to the transmission cables

Question 39

what does a step down transformer do

Answer 39

used to decrease, to a much lower value, the pd for domestic use

Question 40

why is a high pd used to transfer electrical power on the national grid

Answer 40

gives a low current. this reduces the energy losses through heating, increasing efficiency

Question 41

how are electrons transferred between materials

Answer 41

rubbed together, friction removes electrons from one

Question 42

how does a material become negatively charged

Answer 42

gains electrons

Question 43

how does a material become positively charged

Answer 43

loses electrons

Question 44

what happens when 2 materials carrying the same charge are brought close together

Answer 44

they repel each other

Question 45

what happens when 2 materials carrying different charge are brought close together

Answer 45

they attract one another

Question 46

is static charge an example of contact force or non contact force?

Answer 46

non-contact force

Question 47

what surrounds a charged object

Answer 47

electric field

Question 48

what happens to the strength of the electric field with increasing distance from a charged object?

Answer 48

gets weaker

Question 49

draw the electric field around a positively charged sphere

Answer 49

<—+—> more arrows around

Question 50

draw the electric field around a negatively charged sphere

Answer 50

—>-<— more arrows around