Question

A parallel-plate capacitor with only air between the plates is charged by connecting it to a battery. The capacitor is then disconnected from the battery, without any of the charge leaving the plates.

A. A voltmeter reads 44.0 V when placed across the capacitor. When a dielectric is inserted between the plates, completely filling the space, the voltmeter reads 11.0 V . What is the dielectric constant of this material?

B. What will the voltmeter read if the dielectric is now pulled partway out so it fills only one-third of the space between the plates?

Answer 1

cpacitance without dilectric is

C=Q/V₀

and

C_f=Q/V_f  

we have relation

C_f=KC

so Q/V_f=K(Q/V₀)

K=V₀/V_f

= 44/11

K= 4 ANS

(b)

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