Year 12 Part 1

Question 0

What is an insulator?

Answer 0

A material which won’t allow a current to pass through it. Most solids are insulators so are liquids except mercury. Gases too.

Question 1

What is an electrical conductor?

Answer 1

A material which allows electrical current to pass through it. All metals and graphite are insulators.

Question 2

What’s the difference between conductors and insulators?

Answer 2

Conductors have free electrons, insulators don’t.

Question 3

What makes the current?

Answer 3

The drift of electrons

Question 4

What creates the electrical resistance of a metal?

Answer 4

The moving electrons colliding with metal ions.

Question 5

What can increase a metals temperature?

Answer 5

When electrons collide with metal ions they give the ions energy.

Question 6

What is resistance inversely proportional to?

Answer 6

The cross sectional area.

Question 7

What is resistance directly proportional to?

Answer 7

Length

Question 8

What is conventional current?

Answer 8

Flow from positive terminal of power supply round the circuit to the negative end of the power supply.

Question 9

What is an electric current?

Answer 9

Electrons moving. Electrons leave the negative terminal of the power supply and travel round the circuit to the positive terminal.

Question 10

What is electric current measured in?

Answer 10

Collombs, C

Question 11

Signs for equations

Answer 11

Amps-I
Seconds-t
Collombs (Q)-c

Question 12

Whats a switch?

Answer 12

A convenient way of allowing or preventing the flow of current.

Question 13

What’s the difference with a series and parallel circuit?

Answer 13

Series- one current path

Parallel- more than one path for current

Question 14

Whats the current and voltage in a series circuit?

Answer 14

The current is the same everywhere in a series circuit. The individual voltage can be differnt. The supply voltage V equals the sum of the individual voltages across the components

Question 15

Whats the voltage and current in parallel circuits?

Answer 15

The voltage across each branch is the same and equals the supply voltage V.
The total current equals the sum if the currents in the branches.
If the branches are identical then the same current flows in each.

Question 16

What does the slope of a V/I equal?

Answer 16

The resistance of he conductor

Question 17

What is resistance?

Answer 17

Opposition of an object to the flow of current through it

Question 18

What is current directionally proportional to when flowing through a metallic conducter?

Answer 18

Potential difference across it provided all physical conditions are kept constant.

Question 19

In series and in parallel(identical size and different sizes) circuits how does resistance add up?

Answer 19

Series- R1+R2+R3
Parallel-R\2
Parallel (any size)- 1/R equals 1/R1+1/R2+1/R3

Question 20

How does resistance add up in combos?

Answer 20

Equal resistors-R +R/2

Not equal resistors- R parallel is product divide by sum+R

Question 21

What is power?

Answer 21

The rate at which work is done or energy is transferred.

Question 22

What’s a power equation ?

Answer 22

P-E/T
P- power
E-work done
T-time in seconds

Question 23

What colours are wires in a three pin plug?

Answer 23

Live-brown
Earth- green and yellow stripes
Neutral-blue

Question 24

Which wire wires carry current?

Answer 24

Live- carries current to device
Neutral- current from device
Earth- carries none unless fault occurs

Question 25

What’s a circuit breaker?

Answer 25

RCD residual current device compared current in live and neutral wire if they aren’t the same the breaker makes a gap on the live side of the circuit making it safe.

Question 26

What way do magnetic field lines go?

Answer 26

North to South

Question 27

What do the fingers represent on Flemings left hand rule?

Answer 27

Thumb- direction of force
Forefinger- magnetic field
Second finger- direction of current