A parallel plate capacitor with air between the plate has a capacitance of 15pF. The separation between the plate becomes twice and the space between them is filled with a medium of dielectric constant 3.5. Then the capacitance becomes x/4 pF. The value of x i s __________.
Physics · Capacitor · capacitor with dielectric
JEE Mains 24 January 2023 Shift 2 Evening Shift

Question

A parallel plate capacitor with air between the plate has a capacitance of 15pF. The separation between the plate becomes twice and the space between them is filled with a medium of dielectric constant 3.5. Then the capacitance becomes x/4 pF. The value of x i s __________.

Physics · Capacitor · capacitor with dielectric

JEE Mains 24 January 2023 Shift 2 Evening Shift

G1 Physics · Accepted Answer

Initially C₀ = ε₀A/d = 15 pF. After doubling separation and inserting dielectric K = 3.5, C = Kε₀A/(2d) = (3.5/2)C₀ = (3.5/2)(15) = 105/4 pF. Hence x = 105.