Electrostatics Question 260
Question: Six charges, three positive and three negative of equal magnitude are to be placed at the vertices of a regular hexagon such that the electric field at O is double the electric field when only one positive charge of same magnitude is placed at R. Which of the following arrangements of charges is possible for P, Q, R, S, T and U respectively [IIT-JEE (Screening) 2004]
Options:
A) 100 dynes
B) 160 dynes
C) 1600 dynes
D) 400 dynes
Show Answer
Answer:
Correct Answer: A
Solution:
By the concept of electrical image, it is considered that an equal but opposite charge present on the other side of the plate at equal distance. Hence force
$ F=\frac{40\times 40}{4^{2}}=100dynes $
