#### Question

A capacitor stores 50 µC charge when connected across a battery. When the gap between the plates is filled with a dielectric, a charge of 100 µC flows through the battery. Find the dielectric constant of the material inserted.

#### Solution

Given:

Initial charge on the capacitor = 50 µC

Now, let the dielectric constant of the material inserted be k.

As 100 µC of extra charge flows through the battery, the net charge on the capacitor becomes

50 + 100 = 150 µC

Now ,

`C_1 = q_1/V = (∈_0A)/d` ............(i)

`C_2 = q_2/V = (∈_0Ak)/d` ............(ii)

On dividing (*i*) by (*ii*), we get

`C_1/C_2 = q_1/q_2 = 1/k`

⇒ `50/150 = 1/k`

⇒ `k = 3`

Thus, the dielectric constant of the given material is 3.

Is there an error in this question or solution?

Solution A Capacitor Stores 50 µC Charge When Connected Across a Battery. When the Gap Between the Plates is Filled with a Dielectric, a Charge of 100 µC Flows Through the Battery. Concept: Dielectrics and Polarisation.