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A parallel-plate capacitor of capacitance 40 μ F is connected to a 100 V power supply. Now the intermediate space between the plates is filled with a dielectric material of dielectric constant K = 2. Due to the introduction of dielectric material, the extra charge and the change in the electrostatic energy in the capacitor, respectively, are -

1. 2 mC and 0.2 J
2. 8 mC and 2.0 J
3. 4 mC and 0.2 J
4. 2 mC and 0.4 J

Correct answer: 4 mC and 0.2 J

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