Question 2: An electric charge 10–³ μC is placed at the origin (0, 0) of X–Y co-ordinate system. Two points A and B are situated at ( √2, √2) and (2, 0) respectively. Find the potential difference between the points A and B.
\[V_{A} - V_{B}=\frac{kq}{2}\]
\[V_{A} - V_{B}=\frac{kq}{\sqrt{2}}\]
\[V_{A} - V_{B}=9\times 10^{6}\]
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Solution:
The potential \( V \) due to a point charge \( q \) at a distance \( r \) is given by:
\[
V = \frac{kq}{r}
\]
1. Distance from the charge at the origin:
- Point \( A(\sqrt{2}, \sqrt{2}) \): Distance \( r_A = \sqrt{(\sqrt{2})^2 + (\sqrt{2})^2} = \sqrt{4} = 2 \).
- Point \( B(2, 0) \): Distance \( r_B = \sqrt{(2)^2 + 0^2} = 2 \).
2. Potentials at \( A \) and \( B \):
\[
V_A = \frac{kq}{r_A} = \frac{kq}{2}, \quad V_B = \frac{kq}{r_B} = \frac{kq}{2}.
\]
3. Potential difference:
\[
V_A - V_B = \frac{kq}{2} - \frac{kq}{2} = 0.
\]
Thus, \( V_A - V_B = 0 \).
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