Current Electricity

Question 1

State Ohm’s Law

Answer 1

The current flowing through a metallic conductor is directly proportional to the potential difference across the ends of the conductor, provided that temperature and other physical conditions remain constant.

Question 2

Define Potential Difference (scalar)

Answer 2

Potential difference (p.d.) across a component in a circuit is defined as the work done to drive a unit charge through the component.

Question 3

SI Unit of p.d.

Answer 3

V (volt)

Question 4

Formula for p.d.

Answer 4

V=W/Q or E/Q

Question 5

The potential difference between 2 points is 1 volt if…

Answer 5

one joule of electrical energy is converted to other forms when one coulomb of charge flows through it.

Question 6

Define Electromotive Force (e.m.f.), ε.

Answer 6

Electromotive force (e.m.f.) is defined as the work done by a source to drive a unit charge around a complete circuit

Question 7

SI Unit for e.m.f.

Answer 7

V (volt)

Question 8

Formula for e.m.f

Answer 8

ε=W/Q

Question 9

Define Current (scalar)

Answer 9

It is defined as the rate of flow of charge.

Question 10

SI Unit of Current

Answer 10

A

Question 11

Formula of Current

Answer 11

I=Q/t, where Q is the charge in coulombs.

Question 12

Define Resistance (scalar), R

Answer 12

It’s the ratio of potential difference across the components to the current slowing through it.

Question 13

SI Unit of Resistance

Answer 13

Ω (ohm)

Question 14

General Formula of Resistance

Answer 14

R= V/I

Question 15

Formula of Resistance (using resistivity)

Answer 15

R= pL/A
where p is the resistivity of the material in Ωm,
L is the length of the wire
A is its cross-sectional area.