TOPIC P2 - Electricity

Question 1

What is the formula for charge?

Answer 1

Charge = current x time
Q = It

Question 2

What is electric current?

Answer 2

Flow of electric charge

Question 3

Unit of current?

Answer 3

Amperes

Question 4

What is potential difference?

Answer 4

Driving force that pushes the charge round. (V)

Question 5

What is the influence of resistance on current flow

Answer 5

The greater the resistance across a component, the smaller the current that flows

Question 6

Potential difference, current & resistance formula?

Answer 6

Potential difference (volts) = current (Amps) x resistance (ohms)

V=IR

Question 7

What does an Ammeter do? Where must It be placed in relation to the circuit?

Answer 7

Measures current in amps flowing through a wire. It MUST be placed in SERIES

Question 8

What does the voltmeter do? Where must it be placed in relation to the circuit?

Answer 8

Measures potential difference across the wire, in volts. It MUST be placed in PARALLEL around what you are investigating.

Question 9

What sort of resistance do ohmic conductors have?

Answer 9

Constant resistance

Question 10

At a constant temperature what happens to the current flowing through an ohmic conductor?

Answer 10

It is directly proportional to the potential difference across it

Question 11

What does an ohmic conductor graph look like?

Answer 11

Diagonal line from bottom left to top right, Directly proportional

Question 12

What does a Filament lamp graph look like?

Answer 12

Curved - as it gets hotter, less current can flow per p.d meaning the graph becomes shallower

Question 13

What does a diode graph look like?

Answer 13

Current will only flow in one direction. Very high resistance in the reverse direction

Question 14

What is an LDR

Answer 14

A resistor dependent on light. In bright light resistance falls and vice versa

Question 15

What is a Thermistor?

Answer 15

A temperature dependent resistor - in hot conditions resistance drops and vice versa

Question 16

What Is a series circuit?

Answer 16

Different components are connected end to end. Removing one element causes the circuit to break.

Question 17

In a series circuit is potential difference shared?

Answer 17

Yes. V(total)=V(1)+v(2)+….

Question 18

Is the current the same in a series circuit?

Answer 18

Yes, the same current flows through all components. I(1)=I(2)=….

Question 19

What happens to resistance in a series circuit?

Answer 19

Resistance adds up.
R(total)=R(1)+R(2)

Question 20

What is a parallel circuit?

Answer 20

Each component is seprately connected to the +/- of the supply. If you remove one element, the circuit will still function.

Question 21

What is the difference in series and parallel circuits regarding potential difference.

Answer 21

In a parallel circuit potential difference is the same across all components whereas in a series circuit p.d is shared.

Question 22

In a parallel circuit what happens to current?

Answer 22

Current is shared between branches. I(total) = I(1) + I(2)