This document defines electric potential and potential difference. It states that electrons only move through a conductor when there is a difference in electric potential, known as potential difference. Potential difference is defined as the work required to move a single unit of positive charge between two points without producing any acceleration, and is measured in volts. The voltmeter is used to measure potential difference by connecting it in parallel across two points, and works done moving a charge is calculated by multiplying the potential difference in volts by the charge in coulombs.

1. ELECTRICITY
Chapter 12

2. HORIZONTAL
PIPE
Water flow due to Pressure Difference

3. ELECTRIC POTENTIAL
 Electrons move only if there is a difference of
electric pressure called the potential difference
along the conductor.
DEFINITION
 The electric potential at a point is defined as work
done in bringing a unit positive charge from
infinity to that point. The potential difference
between two points is defined as the difference in
electric potentials at the two given points.
INFINITE P

4. 10V 6V
Potential Difference =
(10-6)v = 4v
0V 6V
Potential Difference =
(0-6)v = -6v

5.  Potential difference (V) between two points = Work done
(W)/Charge (Q)
V = W/Q -----(2)
= Joule / Coulomb
= 1 joule / 1 coulomb
1 V = 1 J C–1
 The SI unit of electric potential difference is volt (V),
named after Alessandro Volta (1745 –1827), an Italian
physicist.
 potential difference between two points in a current
carrying conductor when 1 joule of work is done to move a
charge of 1 coulomb from one point to the other is called 1
Volt.

6. VOLTMETER
 The potential difference is measured by means of an
instrument called the voltmeter.
 The voltmeter is always connected in parallel across
the points between which the potential difference is to
be measured.

7. NUMERICAL
 How much work is done in moving a charge of 2 C
across two points having a potential difference 12 V?
 Solution
Q = 2C
V = 12V
V = W/Q
W = VQ
= 12 V × 2 C
= 24 J.

8. HOME ASSIGNMENT
1. Name a device that helps to maintain a potential
difference across a conductor.
2. What is meant by saying that the potential
difference between two points is 1 V?
3. How much energy is given to each coulomb of
charge passing through a 6 V battery?