A point charge produces an electric field of magnitude 5 N C–1 at a distance of 40 cm from it. What is the magnitude of the charge?
Given:
Electric field due to a point charge: E = 5 N C–1
Distance between the point charge and the point at which electric field is produced : r = 40 cm = 0.4 m
Formula used:
Electric field is given as:
E=kq r2
Here , k is a constant and k= 
= 9× 109 Nm2C-2 . q is the point charge .
Substituting we get,
Hence, magnitude of the charge is 8.89× 10-11 C.
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