Electrical quantities

Question 1

Does the current flow from negative to positive or positive to negative?

Answer 1

positive to negative

Question 2

Does the electron flow flow from negative to positive or positive to negative?

Answer 2

negative to positive

Question 3

1 Ampere =

Answer 3

1 coulombs of charge per second

Question 4

What is the unit and symbol for charge?

Answer 4

unit: coulomb
symbol: C

Question 5

What is the unit and symbol for current?

Answer 5

unit: amp
symbol: A

Question 6

Define voltage

Answer 6

the work done by charge passing through an electrical component

Question 7

What is the unit for voltage?

Answer 7

volts

Question 8

What is voltage measured by?

Answer 8

voltmeter

Question 9

What happens if there is an ‘obstacle’ in the middle on a current?

Answer 9

particles waste energy going past it

Question 10

Define EMF (electromotive force)

Answer 10

textbook definition:
the electrical work done by a source, move unit of charge around circuit: the voltage across the terminals of a source

simpler: the amount of energy provided by a power source (like a battery) to each unit of charge as it moves through a circuit. It’s like the “push” or force that makes electric charges flow around the circuit.

Question 11

If cells with EMFs E1 & E2 are connected in series, their combined EMFs are given by:

Answer 11

E = E1 + E2

Question 12

What does P.D. mean?

Answer 12

potential difference

Question 13

1 volt =

Answer 13

1 J of energy to move 1 coulomb of charge

Question 14

When a symbol has an arrow through it, this indicates that…

Answer 14

it’s variable

Question 15

Describe ohmic resistor

Answer 15

has a constant resistance; its current-voltage characteristic is a straight line graph, so that the current through it is directly proportional to the voltage across it. can keep the temp. constant, so the current can easily increase as the voltage increases (constant resistance)

Question 16

Describe the graph

Answer 16

resistor has a constant resistance. current-voltage characteristic is a straight line graph, so that the current through it is directly proportional to the voltage across it

Question 17

Describe the graph

Answer 17

at higher voltages, the graph starts to curve over. the current increases more and more slowly as the voltage is increased. current is not proportional to voltage

Question 18

Which has a higher resistance? Why?

Answer 18

B because its current increases slower than resistor A when potential difference (voltage) increases

Question 19

Define variable resistor

Answer 19

a resistor where resistance can be changed, for example, by turning a knob or moving a slider

Question 20

What are the 3 different types of resistors?

Answer 20

• variable resistor
• LDR
• thermistor

Question 21

Define LDR

Answer 21

a type of resistor whose resistance depends on the amount of light falling on it

Question 22

Define thermistor

Answer 22

a type of resistor whose resistance depends on its enviornment

Question 23

What is Kirchhoff’s first law?

Answer 23

the total current going in to a junction in a circuit is equal to the total current going out of the junction

Question 24

What is Kirchhoff’s second law?

Answer 24

The sum of the EMFs around an closed loop in a circuit is equal to the sum of the p.d. in that loop