CBSE Board Exam & JEE Main 2020: Check Important MCQs (with Answers) from Class 12 Physics - Chapter 2 Electrostatic Potential and Capacitance for Preparation

Get important multiple choice questions for JEE Main & CBSE Board Exams 2020. Here you will get important MCQs for CBSE Class 12 Physics (Chapter 2 Electrostatic Potential and Capacitance). From this year onwards, multiple choice questions will be asked in CBSE Class 12 Physics Board Exam, so the practice of multiple choice questions is also important for the preparation of CBSE Class 12 Physics Board Exam 2020. The questions provided here are based on simple but important concepts and also useful for the preparation of other competitive exams like NEET, WBJEE etc.

Important MCQs: Chapter 2 - Electrostatic Potential and Capacitance

1. A parallel plate capacitor has a capacitance of 50 p Fin air and 105 p F when immersed in oil. The dielectric constant of the oil is:

a) 5.1

b) 1

c) 2.1

d) ∞

Answer: c)

Sol:

Given,

Capacity of capacitor, in air = Co = 50 p F, in water = Cm = 105 p F, dielectric constant = k.

Now, k = Cm/ Co = 105/50 = 2.1.

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3. 100 joule of work is performed in carrying a charge of ‒5 coulomb from infinity to a particular point in anuniform electrostatic field. The potential of this point is:

a) 100 V

b) 5 V

c) -20V

d) 20 V

Answer: c)

Given,

Charge = q = ‒ 5 C, work done = W = 100 Joule.

Let V be the potential then,

As, W = q × V ⇒ 100 = ‒ 5 × V ⇒ V = ‒ 20 V.

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6. Three different capacitors are connected in series. Then:

a) They will have equal charges

b) They will have same potential

c) Both 1 & 2

d) None of these

Answer: a)

When three capacitors are connected in series then the charge in each capacitor is same.

7. If Q is the charge on the capacitor and E is the electric field intensity between the plates, then the force between the plates of a capacitor is

a) QE

b) 2QE

c) QE/2

d) QE/4

Answer: a)

If Q is the charge on the capacitor and E is the electric field intensity between the plates, then the force between the plates of a capacitor is equal to QE/2.

8. A hollow metal sphere of radius 10 cm is charged such that the potential on its surface is 80 volt. The potential at the centre of the sphere is:

a) 8 volt

b) 800 volt

c) 80 volt

d) Zero

Answer: c)

The potential at any point inside the charged metallic hollow sphere is equal to the potential at its surface. Hence, potential at its centre is 80 V.

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