14, 15: COE, DC

Question 1

Define current

Answer 1

Current is the rate of flow of charge

Question 2

Define Drift Velocity

Answer 2

Drift velocity refers to the average velocity of electrons in a conductor under the influence of an electric field

Question 3

Define potential difference

Answer 3

P.d between two points in a circuit is defined as the amount of electrical energy per unit charge that is converted to other forms of energy when charge passes from one point to another

Question 4

Define EMF

Answer 4

EMF of a source is the amount of electric energy that is converted to other forms of energy when the source drives a coulomb** of charge around a complete circuit

Question 5

Define Electrical power

Answer 5

Power is the rate of work done

Question 6

Define resistance/ohm

Answer 6

Resistance of a conductor is the ratio of the p.d across the conductor to the current flowing through it

Question 7

Define Ohms Law

Answer 7

Ohms law states that current I flowing through an electrical conductor is proportional to the p.d across it, provided that temp remains constant.

Question 8

How to find resistance from I-V graph?

Answer 8

Draw lines from the origin and find the gradient of the line

Question 9

Equation for terminal pd

Answer 9

terminal pd = emf - pd across internal resistance

Question 10

Equation for potential divider

Answer 10

pd = (R/Reff)(emf)

Question 11

Equation for drift velocity

Answer 11

I = nAve

I - current
n - no of charge per unit volume
A - CSA
V - drift velocity
e - elementary charge