A capacitor of capacitance ‘C’, is connected across an ac source of voltage V, given by V=V0 sinωt The displacement current between the plates of the capacitor, would then be given by :
Correct Answer :
Id = V0ωCcosωt
Id = V0ωCcosωt
Solution :
The correct option is Id = V0ωCcosωt.
Step-by-Step Explanation:
1. Understanding Capacitor and Voltage:
We are given a capacitor of capacitance connected to an alternating voltage source. The voltage across the capacitor as a function of time is given by:
2. Relation between Charge and Voltage:
The instantaneous charge on the plates of the capacitor at any time is related to the capacitance and the instantaneous voltage across it by the relation:
Substituting the expression for into the equation:
3. Calculating the Displacement Current:
By definition, the displacement current between the plates of a capacitor is equal to the rate of change of charge on its plates, which is also equal to the conduction current in the wires. Mathematically:
Substitute the expression for :
Since and are constants, we can take them out of the derivative:
4. Evaluating the Derivative:
Using the chain rule of differentiation, the derivative of with respect to is :
Rearranging the terms, we get:
Thus, the displacement current between the plates of the capacitor is given by .
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