P2 Electricity

Question 1

What Is the equation for potential difference?

Answer 1

Potential difference = current x resistance V = IR

Question 2

What is current?

Answer 2

Flow of charge per second

Question 3

What moves around a circuit

Answer 3

Electrons

Question 4

What is charge measured in?

Answer 4

Coulombs (C)

Question 5

What is potential difference measured in?

Answer 5

Volts (V)

Question 6

What is resistance measured in?

Answer 6

Ohms

Question 7

What is current measured in?

Answer 7

Amperes/ Amps (A)

Question 8

Which direction does current move in?

Answer 8

The opposite direction to the electrons

Question 9

What is the equation for charge?

Answer 9

Q = It
Charge = current x time

Question 10

What is the rule for current in a series circuit?

Answer 10

Current is the same at all points

Question 11

What is the rule for potential difference in a series circuit?

Answer 11

V1 = V2 + V3

Question 12

What is the rule for potential difference in a parallel circuit?

Answer 12

Pd is the same across all branches

Question 13

What is the rule for current in a parallel circuit?

Answer 13

I1 = I2 +I3

Question 14

What is electrical resistance?

Answer 14

A measure of a components opposition to the flow of current.

Question 15

What happens if the resistance of a variable resistor is increased?

Answer 15

The current will decrease

Question 16

What is an ammeter?

Answer 16

Used to measure current, placed in series

Question 17

What is a voltmeter?

Answer 17

Measures potential difference, placed in parallel

Question 18

How do we collect negative values of current and resistance?

Answer 18

Swap the connecting leads at the terminal of the battery

Question 19

What does ohmic mean?

Answer 19

Directly proportional relationship between current and potential difference

Question 20

What does the graph of a constant resistor look like?

Answer 20

Diagonal straight line through the origin (positive)

Question 21

What does the graph of a filament lamp look like?

Answer 21

F

Question 22

If the line is steep, what is the resistance?

Answer 22

Low

Question 23

How does a filament lamp work?

Answer 23

Delocalised electrons pass through the filament wires and collide with the fixed ions
When the electrons collide with the ions they transfer some energy to the ions
As the pd increases, the number of collisions per second between the electrons and ions increases
As the number of collisions increases, the ions vibrates more
As the temperature increases, the resistance increases

Question 24

What is the rule for resistors in series?

Answer 24

The combined resistance is the same of the resistance of all resistors

Question 25

What is the rule for resistors in parallel?

Answer 25

The combined resistance is lower than the resistance of the lowest resistor

Question 26

What is the equation for specific heat capacity?

Answer 26

Energy = mass x specific heat capacity x change in temp

Question 27

What is a switch?

Answer 27

Breaks or completes the circuit

Question 28

What is a cell?

Answer 28

Pushes electrons around the circuit

Question 29

What is a battery?

Answer 29

Cells joined together

Question 30

What is a lamp?

Answer 30

Electricity heats the lamp, lighting it up

Question 31

What is a fuse?

Answer 31

Melt and break the circuit if the current is too high

Question 32

What is a diode?

Answer 32

In the forward direction it has a low resistance, in the backward direction it has a high resistance.

Question 33

What is a resistor?

Answer 33

Controls the size of the current

Question 34

What is a variable resistor?

Answer 34

A resistor you can manually change.

Question 35

What is a thermistor?

Answer 35

A resistor with a higher resistance in the cold.

Question 36

What is an LDR?

Answer 36

A light dependent resistor. When it's dark it has a higher resistance.

Question 37

What is an LED?

Answer 37

A light emitting diode. Same as a diode but it emits light as well.

Question 38

What do you need to remember in RPA 3 Resistance of a wire?

Answer 38

Turn off the power supply when not taking the readings to stop getting the wire hot. Fix the wire to the ruler so that the wire is straight. Use crocodile clips that make a good contact with the wire.

Question 39

How is the resistance of a wire practical set up?

Answer 39

A wire is placed against a ruler at 10cm in a circuit with a voltmeter and ammeter. Record potential difference and current and calculate resistance. Repeat for 20cm, 30cm, 40cm, 50cm etc.