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Capacitance
Tutorial
Parallel Plate capacitor
1) Capacitance is device used to stored energy and
charge. It consists of two non touching plates which
stores equal and opposite change
2) C is defined as
C=Q/V
3) For parallel plate capacitor,
C=ε0A/d
Where A is the area of cross-section of plate
d is the distance between the plates
With Dielectric in between the plates
C=K ε0A/d
What is Capacitance
4) The electric energy stored in capacitor is given by
Energy=QV/2
=CV2/2 ( as Q=CV)
=Q2/2C ( as V=Q/C)
5) We can find various things with the help the above
formula’s
Capacitance Continued….
Solution
This is a arrangement of the parallel plate capacitor
Here we need the find the electric energy stored
Energy=QV/2=CV2/2=Q2/2C
Here we know Q=q0 And capacitance can be found
out using the formula
C=ε0A/d= ε0 a2/b
So energy =Q2/2C
Capacitance Question
How much energy is stored by the electric field between the
two square plates of a as the length of the side separated by
the distance b. The charges on the plates are equal to q0 and
opposite in sign
42
0
22
0
22
0
2
0
2)/(2 a
bq
ba
q


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