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प्रश्न
When a dielectric slab is gradually inserted between the plates of an isolated parallel-plate capacitor, the energy of the system decreases. What can you conclude about the force on the slab exerted by the electric field?
उत्तर
As the energy of the system decreases, the change in the energy is negative. Force is defined as a negative rate of change of energy with respect to distance.
`F = -(∂U)/(∂x)`
So, as the energy decreases, the force due to the electric field of the capacitor increases when the dielectric is dragged into the capacitor.
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