Insulation constant
Objective:
1- Determination of di-electric constant using a parallel plate capacitor.
2- To study the variation in the resonance frequency with the change in
distance between the two plates of the parallel plate capacitor.
Apparatus:
Audio Oscillator, parallel plate capacitor (circular plates), C.R.O, Resistance Box
and Inductance coil.
Theory:
For air between the two plates of the capacitor,
(1)
A: Area of the plate
d: Distance between the two plates
If there is wooden sheet used as a dielectric,
(2)
From (1) and (2)
At Resonance,
Or:
i.e
(3)
Procedure:
Part A:
1- Make the circuit as shown in the figure.
2- Fit the wooden sheet first gently between the parallel plates of the
capacitor and read the distance on the scale.
3- Note the corresponding resonance frequency.
4- Remove this sheet and keeping the same distance for air between the
two plates, note the resonance frequency again.
5- Repeat the same procedure for the plastic sheet.
6- Calculate K the dielectric constant using equation (3)
Part B:
1- With air in between the plates of the capacitor, note the resonance
frequency for different distance i.e 1mm, 2mm, 3mm,………….8mm
2- Plot a graph between (d) distance and f2 to observe the variation
between these quantities.
C.R..O
Questions:
100mA
Is1 1- Explain the theory of parallel plate capacitor.
2- Explain the Behavior of resistance, capacitor and inductor in A.C.
circuits.
L1
1uH
C1
R1
1uF
RLY2
10
3- Explain the5VCOIL
resonance
in RLC parallel circuit.
4- Explain the effect of di-electrics on capacitance.
Answer all these questions:
1- What is the behavior of R,C,L in alternative current parallel circuit?
2- What is the condition of resonance in RLC parallel circuit?
3- What is the relation between capacitance and di-electric constant?