Electricity

Question 1

what is emf

Answer 1

electromotive force

Question 2

what is emf measured in

Answer 2

volts

Question 3

definition of current

Answer 3

rate of the flow of charge in a circuit or component

Question 4

what is the smallest possible charge (electron charge)?

Answer 4

1.6x10-19

Question 5

what values must charge be

Answer 5

0 or multiple of the electromotive force

Question 6

steps of induced charge given a wall and a balloon rubbed against your head

Answer 6

-balloon becomes negatively charged
-balloon put against wall and like charges repel so electrons repelled to other side of the wall
-opposite charges attract so balloon ‘sticks’ to wall

Question 7

what is direction of conventional current flow

Answer 7

positive to negative

Question 8

what causes a spark

Answer 8

large build up of charge, large p.d. between object and earth causes electrons to jump between gap and cause a spark

Question 9

rule of current in series

Answer 9

I=I=I

Question 10

rule of p.d. in series

Answer 10

V=V+V

Question 11

rule of resistance in series

Answer 11

R=R+R

Question 12

rule of current in parallel

Answer 12

I=I+I

Question 13

rule of p.d. in parallel

Answer 13

V=V=V

Question 14

what happens to resistance if more resistance is added in parallel

Answer 14

resistance of whole circuit decreases as there are more paths for current to flow

Question 14

definition of emf

Answer 14

amount of energy transferred to electrical energy

Question 15

definition of potential difference

Answer 15

amount of energy transferred from electrical to other stores

Question 16

what is an electronvolt

Answer 16

amount of energy an electron gains by passing through 1V

Question 17

what is the value of 1eV

Answer 17

1.6x10-19J

Question 18

what is ohms law

Answer 18

electrical current through a conductor is directly proportional to p.d. and inversely proportional to resistance

Question 19

what is definition of resistance

Answer 19

the opposition to current

Question 20

what is definition of resistivity

Answer 20

fundamental property of a material that measures how strongly it resists electrical current

Question 21

does resistance or resistivity change with length, area

Answer 21

resistance!

Question 22

what is rho

Answer 22

resistivity

Question 23

what is l

Answer 23

length (of wire)

Question 24

on a graph of V against I which variable is on which axis

Answer 24

y-V
x-I

Question 25

on IV graph, how is resistance found?

Answer 25

1/m

Question 26

on VI graph, how is resistance found?

Answer 26

m

Question 27

what does filament bulb IV graph look like and why

Answer 27

S shape because filament gets hot at high voltages so more resistance and less current

Question 28

what does an IV graph for an ohmic conductor look like

Answer 28

straight line through the origin

Question 29

what does an IV graph for a diode look like and why

Answer 29

flat on negative side and then shoots up on other side because diode only lets current flow in one direction

Question 30

IV graph for a thermistor and why

Answer 30

flipped S… because thermistor has lower resistance at higher temperatures

Question 31

VI graph fo