Electrostatics Question 230
Question: A solid metallic sphere has a charge $ +3Q $ . Concentric with this sphere is a conducting spherical shell having charge $ -Q $ . The radius of the sphere is $ a $ and that of the spherical shell is $ b(b>a) $ . What is the electric field at a distance $ R(a<R<b) $ from the centre [MP PMT 1995]
Options:
A) $ \frac{Q}{2\pi {\varepsilon _{0}}R} $
B) $ \frac{3Q}{2\pi {\varepsilon _{0}}R} $
C) $ \frac{3Q}{4\pi {\varepsilon _{0}}R^{2}} $
D) $ \frac{4Q}{4\pi {\varepsilon _{0}}R^{2}} $
Show Answer
Answer:
Correct Answer: C
Solution:
Electric field at a distance R is only due to sphere because electric field due to shell inside it is always zero.
Hence electric field =$ \frac{1}{4\pi {\varepsilon _{0}}}.\frac{3Q}{R^{2}} $
