I reach into the bin of random electronic components and pull out a discharged c
ID: 2275732 • Letter: I
Question
I reach into the bin of random electronic components and pull out a discharged capacitor. If I now put that capacitor across a high-voltage source....
The capacitance will be decreased.
The capacitance will remain unchanged.
The capacitance will be increased.
The change in capacitance will depend on the magnitude and orientation of the battery.
I measure the capacitance, C, of two parallel metal plates with nothing but air between them.
Later in the day, I place a block of paraffin wax between the plates. When I measure the capacitance again....
Inserting the wax will have increased the plates' capacitance.
Inserting the wax will have no effect on the plates' capacitance.
Inserting the wax will have decreased the plates' capacitance.
The effect of the wax is impossible to predict without more specific information.
The capacitance will be decreased.
The capacitance will remain unchanged.
The capacitance will be increased.
The change in capacitance will depend on the magnitude and orientation of the battery.
Explanation / Answer
1)
Capacitance of a capacitor is given by:
C = K*e*A/d
where,
K = dielectric constant of material bertween the plates
e = epsilon = permittivity of free air = 8.85*10-12
A = area of the capacitor.
d = distance of separation between the plates.
We can see from the form of capacitance that the capacitance does not depend upon the voltage difference across it,
So, capacitance wont change <--------------answer
2)
Dielectric constant of air = 1 and
dielectric constant of paraffin wax is greater than 1. So, K >1 for paraffin wax
So, We can see that inserting the wax, will increase the capacitance <------------answer