Electrostatics Question 317
Question: Two electric dipoles of moment P and 64 P are placed in opposite direction on a line at a distance of 25 cm. The electric field will be zero at point between the dipoles whose distance from the dipole of moment P is [MP PET 2003]
Options:
A) 5 cm
B) $ \frac{25}{9} $ cm
C) 10 cm
D) $ \frac{4}{13} $ cm
Show Answer
Answer:
Correct Answer: A
Solution:
Suppose neutral point N lies at a distance x from dipole of moment p or at a distance x2 from dipole of 64 p. At N |E. F. due to dipole |= |E. F. due to dipole ‚| therefore $ \frac{1}{4\pi {\varepsilon _{0}}}.\frac{2p}{x^{3}}=\frac{1}{4\pi {\varepsilon _{0}}}.\frac{2(64p)}{{{(25-x)}^{3}}} $
therefore $ \frac{1}{x^{3}}=\frac{64}{{{(25-x)}^{3}}} $
therefore x = 5 cm.
