4.1-Charge And Current

Question 1

Electric current

Answer 1

• A flow of charge
• measured in ampere (A)

•one amp flows when 1C (6.25 x 10^18 electrons) passes a point in a circuit each second

Question 2

1 coulomb

Answer 2

The amount of charge which flows past a point in a circuit in 1s when the current is 1A

Question 3

Mean drift velocity

Answer 3

The average velocity that a charge carrier (eg. electron) attains in a material due to an electric field

Question 4

Kirchhoff’s first law

Answer 4

The sum of a current entering a junction in a circuit is equal to the sum of the currents leaving the junction of the circuit

(Conservation of charge, cannot be created or destroyed)

Question 5

State what each stand for:
I= navq

Answer 5

I- Current (A)
n- number of charge carriers
a- cross sectional area (m^2)
v- drift velocity (m/s)
q- charge (C)

Question 6

Charge carrier density

Answer 6

How many electrons/ions are available to carry charge through a circuit

Question 7

Rule for adding resistors in series

Answer 7

Rₜ = R₁ + R₂ + ….

Question 8

Rule for adding resistors in parallel

Answer 8

⅟Rₜ = ⅟R₁ + ⅟R₂ + ….

Question 9

Direction of conventional current

Answer 9

Flows from positive to negative

Question 10

Quantised

Answer 10

Grouping a unit to make it easier to understand

Eg. Rather than counting individual electrons it’s easier to measure in coulombs

Question 11

Direction of electron flow

Answer 11

From negative to positive

Question 12

Electrolyte

Answer 12

A liquid containing charged ions

Question 13

Cation

Answer 13

Positively charged ion

Question 14

Anion

Answer 14

Negatively charged ion

Question 15

Cathode

Answer 15

Negatively charged electrode

Question 16

Anode

Answer 16

Positively charged electrode