Question

Calculate the work done in bringing a unit positive test charge from a point with potential 200 V to a point at potential 100 V.

• A. 50 J
• B. 100 J
• C. 150 J
• D. 200 J

Answer 1

The correct option is B

100 J

Given: Initial potential, $V_1=200V$

and final potential, $V_2=100V$

Potential difference, $V=V_2-V_1$
$V=200-100=100V$

Since it is unit positive test charge, charge Q = 1C

We know that potential difference, $V=\frac{W}{Q}$ (where W is work done and Q is charge)

$\Rightarrow$ $W=V\times Q$

$\Rightarrow$ $W=100V\times 1C=100J$

Therefore, work done to bring a unit positive test charge from a point with potential 200 V to a point at potential of 100 V​​​​​​ is 100J.