Q145 / 160 · AP EAMCET 2024 (21 May Shift 2) · Physics
When a parallel plate capacitor is charged up to 95 V , its capacitance is C. If a dielectric slab of thickness 2 mm is inserted between plates and distance between the plates is increased by 1.6 mm such that the same potential difference is maintained. The dielectric constant of the material (slab) is
- A2.4
- B4.5
- Correct answerC5.0
- D9.0
Solution
When the battery is removed,
$\begin{aligned} & Q=\text { constant } \\ & \Rightarrow C_1 V=C_2 V \Rightarrow C_1=C_2 \\ & \Rightarrow \frac{\varepsilon_0 A}{d}=\frac{\varepsilon_0 A}{(d+1.6)-t\left(1-\frac{1}{k}\right)} \\ & \therefore d=(d+1.6)-2\left(1-\frac{1}{k}\right) \\ & \therefore \quad K=5 \end{aligned}$
$\begin{aligned} & Q=\text { constant } \\ & \Rightarrow C_1 V=C_2 V \Rightarrow C_1=C_2 \\ & \Rightarrow \frac{\varepsilon_0 A}{d}=\frac{\varepsilon_0 A}{(d+1.6)-t\left(1-\frac{1}{k}\right)} \\ & \therefore d=(d+1.6)-2\left(1-\frac{1}{k}\right) \\ & \therefore \quad K=5 \end{aligned}$
Hence, the correct answer is option: 'C'.