Question

Two charges of –4mC and +4mC are placed at points A (1,0,4) and B (2, –1,5) located in an electric field $\overset{\rightarrow}{E}$ = 0.20 $\widehat{i}$ V/cm. The torque acting on the dipole is –

• A. 8 × 10^–5 N-m
• B. 8/$\sqrt{2}$ × 10^–5 N-m
• C. 8$\sqrt{2}$ × 10^–5 N-m
• D. $2\sqrt{2}$ × 10^–5 N-m

Answer 1

Answer: (C)

8$\sqrt{2}$ × 10^–5 N-m

Answer 2

= $\overrightarrow { \mathrm { p } }$ × = q (2) ×

Here 2 = (2 – 1) + (– 1–0) + (5 – 4)

=– +

= 0.20 V/cm = 20 V/m

\ = (4 × 10^–6)

= 8 × 10^–5

Magnitude of torque t = 8$\sqrt { 2 }$ × 10^–5 N-m