COMEDK Exam 2017 Solved Paper

Given, capacitance of air filled parallel plate capacitor,
⇒‌C0‌=2‌pF
‌=2×10−12F
⇒‌‌

ε0A

d

‌=2×10−12F . . . (i)
When the separation between the plates is doubled, i.e., ‌‌d′=2d
And wax of dielectric constant k is filled between the plates of capacitor, then,
C′‌=6‌pF‌
‌

ε0kA

d′

‌=6×10−12F‌
⇒‌‌‌

ε0kA

2d

‌=6×10−12‌ [∵d′=2d]
⇒‌‌‌

ε0A

d

×‌

k

2

‌=6×10−12‌
⇒2×10−12×‌

k

2

‌=6×10−12‌ [from Eq. (i)]
⇒‌‌k=6