Question

A bulb B a capacitor C are connected in series to an a.c. source. A dielectric slab is now introduced between the plates of the capacitor. How will the brightness of bulb change ?

Answer 1

Current through the bulb is
`I_(v) = (E_(v))/(Z) = (E_(v))/(sqrt(2) + (1)/(omega^(2) C^(2)))` On introducing a dielectric slab between the plates of capacitor, C increases. Z decreases, `I_(v)` increases. Therefore, glow of the bulb increases.