Y1 Ch 13 & 14 Current Electricity and

Question 1

Current Definition

Answer 1

The rate of flow of electrons.

Question 2

Current =

Answer 2

Charge/Time

Question 3

Direction of current

Answer 3

From positive to negative.

Question 4

Current - Vector or Scalar

Answer 4

Vector

Question 5

A gradient of a Q/t graph is

Answer 5

the current.

Question 6

The area beneath an I/t graph is the

Answer 6

Charge.

Question 7

Potential Difference Definition

Answer 7

Work done per unit charge between two points.

Question 8

P.D. =

Answer 8

Work Done/Charge

Question 9

Electromotive force definition

Answer 9

Energy supplied per unit charge by the supply.

Question 10

p.d. - Vector or Scalar

Answer 10

Vector.

Question 11

Resistance definition

Answer 11

The opposition to current flow.

Question 12

Resistance =

Answer 12

P.d./Current

Question 13

Superconductor

Answer 13

A material that has 0 resistance below its critical temperature.

Question 14

Thermistors

Answer 14

A temperature dependent resistor.

Question 15

As the temperature increases the resistance of a thermistor

Answer 15

decreases

Question 16

Resistivity equation

Answer 16

R = Resistivity * L/A

Question 17

Ammeters

Answer 17

placed in series, therefore, have no resistance.

Question 18

If the resistance of an ammeter increases

Answer 18

The current and p.d. will decrease.

Question 19

Voltmeter

Answer 19

Placed in series so has infinite resistance

Question 20

If the resistance of a voltmeter decreases

Answer 20

The current of the component will decrease but the p.d. will stay the same. The overall resistance will decrease therefore total current will also increase.

Question 21

Cells - with negligible internal resistance

Answer 21

If they are in series add together. If they are in parallel the total emf is equal to the emf of one of the cells if they are identical.

Question 22

Cells - with internal resistance in series

Answer 22

emf = nemf and R = nr

Question 23

Cells - with internal resistance in parallel

Answer 23

emf = emf and R = r/n

Question 24

Power definition

Answer 24

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

Question 25

Power equation

Answer 25

P = W/T = VQ/T = VIT/T = IV

Question 26

Current in a series circuit

Answer 26

The same across the circuit

Question 27

P.d in a series circuit

Answer 27

emf = sum of p.d. across each component - Kirchhoff's second law.

Question 28

Resistance in a series circuit

Answer 28

Total resistance = sum of resistances

Question 29

Current in a parallel circuit

Answer 29

total current = total current across all branches Kirchhoff's first law.

Question 30

Potential difference in a parallel circuit

Answer 30

p.d. between 2 points is the same for every loop.

Question 31

Resistance in a parallel circuit

Answer 31

1/Rt = 1/R1 + 1/R2 + ...

Question 32

Contact resistance

Answer 32

Resistance between connections.

Question 33

Internal resistance

Answer 33

The resistance inside the power supply

Question 34

On a V/I Graph the gradient is

Answer 34

Internal resistance

Question 35

On a V/I graph the y-intercept is

Answer 35

The Emf

Question 36

Potential divider equation

Answer 36

V1 = Vin * R1/(R1 + R2)

Question 37

Potential dividers with thermistors when hot

Answer 37

The thermistor will take out a low proportion of p.d.

Question 38

Potential divider with thermistors when cold

Answer 38

The thermistor will take out a high proportion of p.d.