Question

There are two points A and B both are having potential V_A = -15 V, V_B = 5V respectively. Find out the work done to move charge q = 5 C from A to B? 
1. 10 J
2. 100 J
3. 50 J
4. 500 J

Answer 1

Correct Answer - Option 2 : 100 J

CONCEPT: 

• The amount of work done in moving a unit positive charge in an electric field from one point to another point without accelerating the charge against the direction of the electric field is known as electrostatic potential.
• The electrostatic potential is given by

\(\Rightarrow V_{B} -V_{A} = \frac{W}{q}\)

Where V_B = Electrostatic potential at B V_A = Electrostatic potential at A, W = Work done, q= Charge

EXPLANATION :

Given  - VA = -15 V,VB = 5V, and q = 5 C

• The work done in moving  the charge 5 μC from one point to another point is given by 

\(\Rightarrow V_{B} -V_{A} = \frac{W}{q}\)

Substituting the given values in the above equation

\(\Rightarrow5 - -15= \frac{W}{5}\)

\(\Rightarrow W = 5\times (20) = 100 J\)

• Hence option 2 is the answer