Question

The distance between the plates of a parallel plate condenser is 120 volts. If a thick slab of dielectric constant 6 is introduced between its plates, then

• 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

Answer 1

Answer: (D)

The P.D. across the condenser will be 45 volts

Answer 2

If nothing is said, it is considered that battery is disconnected. Hence charge remain the same

Also and $V _ { \text {medium } } = \frac { \sigma } { \varepsilon _ { 0 } } \left( d - t + \frac { t } { k } \right)$

⇒$\frac { V _ { m } } { V _ { a } } = \frac { \left( d - t + \frac { t } { k } \right) } { d }$ ⇒ $\frac { V _ { m } } { 120 } = \frac { \left( 8 - 6 + \frac { 6 } { 6 } \right) } { 8 }$ ⇒ V_m = 45V