Question

The electric intensity due to a dipole of length 10 cm and having a charge of $500\mu C$, at a point on the axis at a distance 20 cm from one of the charges in air, is

• A. $6.25 \times 10^{7}$ N/C
• B. $9.28 \times 10^{7}$ N/C
• C. $13.1 \times 11^{11}$ N/C
• D. $20.5 \times 10^{7}$ N/C

Answer 1

Answer: (A)

$6.25 \times 10^{7}$ N/C

Answer 2

By using $E = 9 \times 10^{9}.\frac{2pr}{(r^{2} - l^{2})^{2}};$ where

p = (500 × 10^–6) × (10 × 10^–2) = 5 × 10^–5 $c \times m$,

r = 25 cm = 0.25 m, l = 5 cm = 0.05 m

$E = \frac{9 \times 10^{9} \times 2 \times 5 \times 10^{- 5} \times 0.25}{\{(0.25)^{2} - (0.05)^{2}\}^{2}}$ $= 6.25 \times 10^{7}N ⥂ / ⥂ C$