Assertion: A parallel plate capacitor is charged to a potential difference `100 V`, and disconnected from the voltage source. A slab of dielectric is then slowly inserted between the plates. Compared to the energy before the slab was inserted, the energy stored in the capacitor with the dielectric is decreased.
Reason: When we insert a dielectric the plates of a capacitor, the induced tend to draw in the dielectric into the field (just as neutral). we resist this force while slowly inserting the dielectric, and thus do negative work on the system, removing electrostatic energy from the system.

Options

A. If both assertion and reason are true and reson is the correct explanation of assertion.
B. If both assertion and reason are true but reason is not the correct explanation of assertion.
C. If assertion is true but reason is false.
D. If assertion and reason both are false.

Answer

A

Explanation

In an isolated charged capacitor the potential energy stored is decreased on insertion of dielctric because in expression `U = (Q^(2))/(2C, C` increases on insertion of dielectric.
Hence, Reason is correct and correct explanation of Assertion.