Question

Charges are placed on the vértices of a square as shown. Let$\overset{\rightarrow}{E}$ be the electric field and V the potential at the centre. If the charges on A and B are interchanged with those on D and C respectively, then –

• A. $\overset{\rightarrow}{E}$ remains unchanged, V changes
• B. Both $\overset{\rightarrow}{E}$ and V changes
• C. $\overset{\rightarrow}{E}$and V remains unchanged
• D. $\overset{\rightarrow}{E}$changes, V remains unchanged

Answer 1

Answer: (D)

$\overset{\rightarrow}{E}$changes, V remains unchanged

Answer 2

E_x = –= –$\left( \frac { 20 } { x ^ { 2 } - 4 } \right)$=

E_x ==$\frac { 40 \times 4 } { 144 }$=$\frac { 10 } { 9 }$ in + x direction.