P10

Question 1

circuit symbols

Answer 1

look at picture

Question 2

difference between series and parallel

Answer 2

paralell-two+ loops
series-one loop

Question 3

volotmneter use

Answer 3

connected into parallel circuit with a componenet to measure potential difference(voltage) across it

Question 4

voltage/potential diff def

Answer 4

energy transferred per unit charge passed and hence that the volt is a joule per coulomb

Question 5

energy transferred equation

Answer 5

charge moved(c)(Q) x potential diff(V)

Question 6

ammeter use

Answer 6

connected in a series with a componenet to measure current in amps in the componenent

Question 7

current def

Answer 7

electric-rate of flow of charge
current in metals-a flow of electrons

Question 8

charge equation

Answer 8

current(a) x time (s)

Question 9

when is there a current in a ciruit

Answer 9

when a closed circuit inc;udeas a source of potential difference

Question 10

where is current conserved

Answer 10

at a junction in a circuit

Question 11

how changing resistaqnce in a circuit affects current

Answer 11

with a variable resistor
increasing the resistance for a certain potential diff in a circuit will reduce the current passing through.(ohms law)

Question 12

pd=

Answer 12

current(a) x resistance(ohm)

Question 13

why two resistoras in a series = net res increases
and why 2 in paralell=net res decrease

Answer 13

series-current must flow through both of them so resistance inc
paralell-current only flow through one or the other then overall res is reduced

Question 14

current pd and res in series

Answer 14

current-same wherever measures in circuit
pd-shared between all components
res-total res=all res added up

Question 15

how current varies with pd and how relkates to res in
filament lamps
diodes
fixed resistors

Answer 15

current is directly proportional to pd ansd inversley prop to res

Question 16

how LDR resistance depends on light intensity

Answer 16

resistance decreases as light intewnsity increases

Question 17

how res of a thermistor chnages with temp change

Answer 17

resistance decreases as temp increases

Question 18

when there is an electrical current in a resistor …

Answer 18

there is an energy transfer which heats the resisitor
as a result of collisions between elctrons and the ions in the lattice

Question 19

when an electrical current does wokr against electrical res …

Answer 19

elec energy is dissipated as thermal energy in the surroundings

Question 20

how to reduce unwanted energy transfers

Answer 20

through low res wires reduce transfers to thermal stores as current flows through components

Question 21

ad and disadvantages of heating effect of an electrical current

Answer 21

ad-
kettles
ovens
heating
toasters
dis-
reduces efficiency trhough energy loss
can pose fire hazard(too much current through low quality wires)
reduces lifetime of sevral components in cirucit

Question 22

energy transferred(J)=

Answer 22

current(a) x pd x time(s)

Question 23

power def

Answer 23

energy transferred per second and measured in watts

Question 24

power(w)=

Answer 24

energy trasferred(J)/time taken(s)

Question 25

how power transfer in any circuit device is related to pd across it and current in it

Answer 25

power is equal to the product odf current and potential diffewrencde

Question 26

elec power(w)=

Answer 26

current x pd
or
= current squared(a^2) x res(ohm)

Question 27

how energy is transferred from batteries and the a.c. mains to the enrgy of motors and heating devices

Answer 27

heating devices convert elec energy from maisn ac supply into thermal energy or kinetic energy which can then be used for its puropose

Question 28

difference between dircet and alternatimng voltage

Answer 28

direct-produces a constant electric current that flows in one direcvtion
alternating-produces an alternating curent that changes direction regularly

Question 29

direct current

Answer 29

movement of charge in one direction only and cells and batteriews supply direct current

Question 30

ac

Answer 30

movement if charge changes direction

Question 31

uk domestic supply ac

Answer 31

50 Hz(frequency)
230 V(voltage)

Question 32

difference in function between the live and neutral mains input wires

Answer 32

live-carries full load current
neutral-carries some curreent only when the loads are nit balanced

Question 33

functionnof earth wires and of fuses or circuit breakers in ensuring safety

Answer 33

breakers qand fuses- protect the wiring from damage caused by too much electricla current flowing through the cxircuit
earthing-used to protect ypu from an electric shock
by providing a pathg ( a protective conductor) for a fault cureent to flow to earth

Question 34

why switches and fuses should be connected in the live wire of a domestic circuit

Answer 34

to ensure that it keeps the high voltage from reavhing the sueer or surroundiungs if as fsuklt develops because the live wire carriesfullm looad current so controls it when gets too high

Question 35

pd’s between live, neutral and erath main wires

Answer 35

earth-0 V
neutral - 0V
live- 230 V

Question 36

dangers of providing any connection between live wire and earth

Answer 36

a shock or a firw would be highly likely even if circuit switched off live wire can still be damngerousw
if ytou touch it you may conplet the cirtcuit between the live wire and the floor (when switch open) so you get a shock

Question 37

realtionship between a devices power ratimng and chnages in stored energy when used

Answer 37

devuce with higher power rating will transfer stored energy to other types of energy at a faster rate

Question 38

parallel circuits

Answer 38

current-splits at different branches then combines again before returning to power supply
pd-same everywher in circuit
res-overaqll res reduced with 1 or more res as current can follows multiple paths