The voltage across an airfilled parallelplate capacitor is m

The voltage across an air-filled parallel-plate capacitor is measured to be 154.0 V. When a dielectric is inserted and completely fills the space between the plates as in the figure below, the voltage drops to 45.3 V. What is the dielectric constant of the inserted material? Can you identify the dielectric? If the dielectric doesn\'t completely fill the space between the plates, what could you conclude about the voltage across the plates?

Solution

a)

When the dielectric (with dielectric constant k ) is inserted, the capacitance changes to k times

So, Voltage must drop be k times <---- from the equation, Q = CV

where Q = charge

C = capacitance

V = voltage

As C changes to k times V must decrease to times so that the charge Q remains constant

So, k = V1/ V2 = 154/45.3 = 3.4 <--------answer

b)

As dielectric constant of nylon is 3.4

So, answer is nylon <-------answer

c)

If the dielectric does not completely fill the space, the capacitance will increase, and thus the voltage will drop