Question

A spherical capacitor has an inner sphere of radius 10 cm and an outer sphere of radius 11 cm. The outer sphere is earthed and the inner sphere is given a charge of $3.4\mu C$. The space between the concentric sphere is filled with a liquid of dielectric constant 28. The capacitance of capacitor is.

• A. $2 \times 10^{- 9}F$
• B. $3.4 \times 10^{- 9}F$
• C. $4.1 \times 10^{- 9}F$
• D. $5.2 \times 10^{- 9}F$

Answer 1

Answer: (B)

$3.4 \times 10^{- 9}F$

Answer 2

: Here, inner radius, $r_{i} = 10cm = 10 \times 10^{- 2}m$

Outer radius, $r_{o} = 11cm = 11 \times 10^{- 2}m$

Charge, $q = 3.2\mu C = 3.2 \times 10^{- 6}C$and $\varepsilon_{r} = 28$

Capacitance,

}\left\lbrack \frac{28 \times 10 \times 10^{- 2} \times 11 \times 10^{- 2}}{(11 - 10) \times 10^{- 2}} \right\rbrack$$ $= 3.42 \times 10^{- 9}F$