Electricty

Question 1

Electric Current

Answer 1

The rate of flow of charge

Question 2

Coulomb

Answer 2

The unit of charge

Question 3

Elementary charge e

Answer 3

1.6 × 10–19 C

Question 4

Quantised

Answer 4

Net charge on a particle or an object is a multiple of e

Question 5

Current in Metals

Answer 5

Movement of electrons

Question 6

Current in Liquids

Answer 6

Movement of ions

Question 7

Conventional Current

Answer 7

Moves from positive to negative

Question 8

Electron flow

Answer 8

Moves from negative to positive.

Question 9

Kirchhoff’s first law

Answer 9

The sum of currents flowing into a junction is always equal to the sum of currents flowing out of the same junction

Question 10

I (symbol)

Answer 10

Current

Question 11

A (symbol)

Answer 11

Area of cross section

Question 12

n (symbol)

Answer 12

Number density

Question 13

e (symbol)

Answer 13

Elementary charge

Question 14

v (symbol)

Answer 14

Mean drift velocity

Question 15

Conductors Number density

Answer 15

High

Question 16

Insulators Number Density

Answer 16

Low

Question 17

Potential Difference Definition

Answer 17

How much energy each unit per unit charge is being transferred at each component.

Question 18

Electromotive force

E.M.F Definition

Answer 18

Is equal to the maximum (terminal) Pd when no current flows

Question 19

How is resistance caused?

Answer 19

Resistance is cuased by collisions between electrons and the positive ions

Question 20

R(symbol)

Answer 20

Resistance

Question 21

ρ (symbol)

Answer 21

Resistivity

Question 22

L (symbol)

Answer 22

Length

Question 23

A (symbol)

Answer 23

Area

Question 24

E.M.F vs Pd in terms of energy transfer

Answer 24

E.M.F is the quantity that each coulomb of charge receives, P.D is the quantity of energy that each coloumb of charge uses.

Question 25

Kirchoffs Second Law

Answer 25

In any circuit, the sum of electromotive forces is equal to the sum of p.d.s around a closed loop ∑ε = ∑V$, where ∑ε is the sum of the e.m.f.s and ∑V is the sum of the p.d.s.

Question 26

Current in a series circuit

Answer 26

The current is the same in every position, the charge is not used up, it just flows around the circuit

Question 27

P.d in a series circuit

Answer 27

The total e.m.f is the sum of the p.d across the components which is split based on the ratio of the resistances

Question 28

How is p.d split in a series circuit?

Answer 28

The component with the greater resistance will take the greater proportion of the e.m.f as p.d

Question 29

Current in a parallel circuit

Answer 29

The greater the resistance of the branch the lower the current that passes through it, if one branch has half the resistance of the other, it will have twice the current through it

Question 30

Resistors in series (equation)

Answer 30

R = R_1 +R_2 + ...

Question 31

Resistors in Parallel (equation)

Answer 31

1/R = 1/R_1 +1/R_2 +...

Question 32

What are a lost volts?

Answer 32

When there is a current in a power source, work has to be done by the charges as they move through the power source so some energy is lost

Question 33

What does increasing the current do to the lost volts?

Answer 33

Increasing the current means that more charge travels through the cell increasing the lost volts and decreasing the terminal p.d

Question 34

Internal Resistance Equation

Answer 34

ε = V + Ir

Question 35

What is the y intercept of a V against I graph mean?

Answer 35

It is the e.m.f

Question 36

What is the gradient of a V against I graph?

Answer 36

The gradient is the negative current