P4.2 - current/charge/volatge/resistance

Question 1

electric current

Answer 1

-flow of charge
-more electron flow per sec = bigger current

Question 2

size of current =

Answer 2

rate of flow of charge
or charge per sec

Question 3

electric charge unit

Answer 3

coulombs C

Question 4

Current unit

Answer 4

amperes A

Question 5

1 amp = how many c

Answer 5

1C per sec

Question 6

equation for charge flow, current, time

Answer 6

charge = current x time

Question 7

conventional flow

Answer 7

-positive to negative

Question 8

electron flow

Answer 8

-negative to positive

Question 9

Components of a circuit: cell

Answer 9

-pushes electrons around circuit

Question 10

Components of a circuit: battery

Answer 10

2 or more cells

Question 11

Components of a circuit: switch

Answer 11

-enables current to turned on/off

Question 12

Components of a circuit: lamp

Answer 12

-emits light when current passes through

Question 13

Components of a circuit: diode

Answer 13

allows current through one direction only

Question 14

Components of a circuit: LED (light-emitting diode)

Answer 14

emits light when current passes the right way

Question 15

Components of a circuit: ammeter

Answer 15

measures current

Question 16

Components of a circuit: fixed resistor

Answer 16

limits current in a circuit

Question 17

Components of a circuit: variable resistor

Answer 17

allows current to be varied

Question 18

Components of a circuit: fuse

Answer 18

melts and breaks circuit if current it too big
-safety mechanism

Question 19

Components of a circuit: heater

Answer 19

-transfer energy from current to heat surroundings

Question 20

Components of a circuit: voltmeter

Answer 20

measures P.D / voltage
Has to be parallel to the thing it’s measuring

Question 21

potential difference

Answer 21

-energy transferred to component that passes through it

Question 22

equation involving pd/energy/charge

Answer 22

P.D = energy transferred/charge

Question 23

resistance

Answer 23

-electrons passing through components have to push their way through lots of vibrating atoms
=resistance

Question 24

equation involving resistance/voltage/current

Answer 24

R=V/I

Question 25

unit for resistance

Answer 25

ohms

Question 26

larger resistance .. =

Answer 26

lower current

Question 27

ohms' law states

Answer 27

-current passing through the resistor at a constant temp -is directly proportional to PD of resistor

Question 28

ohmic conductor

Answer 28

resistance stays constant as current changes -when temp is constant = obeys ohms law

Question 29

reversing pd across resistor =

Answer 29

reverses current

Question 30

non ohmic conductor eg

Answer 30

filament lamp diode

Question 31

non ohmic conductor - filament lamp

Answer 31

-resistance isn't constant -charge depends on current -not proportional -higher current = more resistance as temp increases

Question 32

non ohmic conductor - diode

Answer 32

-low resistance in forward direction -high resistance in the reverse direction

Question 33

ohmic conductor IV graph

Answer 33

-straight line -goes through origin - directly proportional

Question 34

non ohmic conductor - filament lamp

Answer 34

-curved line -not proportional

Question 35

non ohmic conductor - diode

Answer 35

-forward direction line curves towards y axis -reverse direction current = 0

Question 36

thermistors

Answer 36

temp dependent resistor -resistance decreases if temp increases

Question 37

LED

Answer 37

-decreases resistance if the light intensity increases

Question 38

series circuits

Answer 38

consist of one loop of wire

Question 39

current in series circuits

Answer 39

-same current through each component

Question 40

series circuits - PD

Answer 40

-total pd is shared between components

Question 41

series circuits - resistance

Answer 41

-total R = R1+R2

Question 42

Parallel circuits

Answer 42

consists of 2 or more loops of wire

Question 43

Parallel circuits - pd

Answer 43

-pd is same across all components

Question 44

Parallel circuits - current

Answer 44

-total current = sum of current through components on each loop

Question 45

Parallel circuits - resistance

Answer 45

-total resistance is less than the resistance of the smallest resistor -1/R1 + 1/R2 = Rt

Question 46

Light dependent resister or LDR

Answer 46

High light intensity - low resistance