electricity

Question 1

what are the two types of electrical charge

Answer 1

positive and negative

Question 2

what are neutral charges

Answer 2

they have no electrical charge

Question 3

do like charges repel or attract

Answer 3

repel

Question 4

do opposite charges repel or attract

Answer 4

attract

Question 5

what is the nucleus of an atom made up of

Answer 5

protons (+) and neutrons (=)

Question 6

what orbits the nucleus of an atom

Answer 6

electrons (-)

Question 7

what are conductors

Answer 7

materials that allow current to pass through them

Question 8

what are insulators

Answer 8

materials that do not allow current to pass through them

Question 9

what is electrical current

Answer 9

the electric charge transferred per second/unit time

Question 10

Q=It

Answer 10

charge (C) = current (A) time (s)

Question 11

what does a cell do

Answer 11

provide voltage

Question 12

what does a battery do

Answer 12

provide voltage

Question 13

what does a lamp do

Answer 13

produces light

Question 14

what does a switch do

Answer 14

control a circuit (on/off)

Question 15

what does a resistor do

Answer 15

control resistance (fixed)

Question 16

what does a variable resistor do

Answer 16

to control resistance (variable)

Question 17

what does a voltmeter do

Answer 17

measure voltage

Question 18

what does a ammeter do

Answer 18

measure current

Question 19

what does a motor do

Answer 19

produce rotational movement

Question 20

current in a series circuit ____

Answer 20

is the same at every point

Question 21

the current in a parallel circuit’s branches ____

Answer 21

add up to the supply current

Question 22

what is voltage a measure of

Answer 22

the electrical energy given to each coulomb of charge in a circuit

Question 23

the voltage across all the components in a series circuit _____

Answer 23

add up to the supply voltage

Question 24

the voltage across the branches of a parallel circuit ____

Answer 24

are the same as the supply voltage

Question 25

in a.c., the flow of electrons does what

Answer 25

continually changes direction back and forth

Question 26

in d.c., the flow of electrons does what

Answer 26

stays in the same direction

Question 27

example of an a.c. source

Answer 27

UK mains power supply (230V)

Question 28

example of a d.c. source

Answer 28

batteries and cells

Question 29

how to calculate resistance in a series circuit

Answer 29

R(total) = R(1) + R(2) + ....

Question 30

resistors in parallel circuits

Answer 30

1/R(T) = 1/R(1) + 1/R(2) + ....

Question 31

V=IR

Answer 31

voltage (V) = current (A) resistance (Ω)

Question 32

what can variable resistors be used for

Answer 32

dimmer switches and volume controls

Question 33

what does the resistance of an LDR vary with

Answer 33

light levels, light up resistance down

Question 34

what does the resistance of a thermistor vary with

Answer 34

temperature, temp up resistance down

Question 35

what does a photovoltaic/solar cell do

Answer 35

converts light energy to electrical engery

Question 36

what does a diode do

Answer 36

it only allows current to flow in one direction

Question 37

what way should the diode be to allow current to flow

Answer 37

the anode on the power supply should be connected to the diode and the two cathodes should also be connected

Question 38

what does LED stand for

Answer 38

light emitting diode

Question 39

what does a capacitor do

Answer 39

it stores electrical charge

Question 40

what does a relay switch do

Answer 40

the coil in one circuit becomes magnetised, which close the switch in the second circuit

Question 41

in a potential divider, the higher the resistance the ____ the voltage across it is

Answer 41

higher

Question 42

potential divider formulas

Answer 42

V2 = ( R1 / R1 + R2 ) Vs , V1/V2 = R1/R2

Question 43

what can transistors be used as

Answer 43

electronic switches in circuits

Question 44

what is the switch on voltage for a NPN transistor

Answer 44

about 0.7V

Question 45

what does the variable resistor do in a potential divider circuit with a transistor

Answer 45

changes when the circuit switches on and off

Question 46

what voltage do MOSFETs switch on at

Answer 46

about 2V

Question 47

what is power a measure of (not rate)

Answer 47

the energy transferred per second

Question 48

P=E/t

Answer 48

power (W) = energy (J) / time (s)

Question 49

what is electrical power (not per second)

Answer 49

the rate at which electrical energy is transferred

Question 50

when should a 3A fuse be used

Answer 50

if an appliance has a power rating of less than 720W

Question 51

when should a 13A fuse be used

Answer 51

if an appliance has a power rating greater than 720W