Electrostatics Question 35
Question: The distance between the plates of a parallel plate condenser is $ 8mm $ and P.D. $ 120\ volts $ . If a $ 6mm $ thick slab of dielectric constant 6 is introduced between its plates, then
Options:
A) The charge on the condenser will be doubled
B) The charge on the condenser will be reduced to half
C) The P.D. across the condenser will be $ 320\ volts $
D) The P.D. across the condenser will be $ 45\ volts $
Show Answer
Answer:
Correct Answer: D
Solution:
If nothing is said, it is considered that battery is disconnected.
Hence charge remain the same Also $ V _{air}=\frac{\sigma }{{\varepsilon _{0}}}\times d $
and $ V _{medium}=\frac{\sigma }{{\varepsilon _{0}}}(d-t+\frac{t}{k}) $
therefore $ \frac{V _{m}}{V _{a}}=\frac{(d-t+\frac{t}{k})}{d} $
therefore $ \frac{V _{m}}{120}=\frac{(8-6+\frac{6}{6})}{8} $
therefore Vm = 45V
