# MCQ | Capacitor

QUIZ TEST-I

Question:1. The equivalent capacitance between A and B is (A) C

(B) 2C

(C) 1.5C

(D) none of the above

Ans: (A)

Question:2. In the circuit shown in the figure, the capacitor C is charged to a potential Vo. The heat generated in the circuit when the switch S is closed, is (A) C Vo2

(B) 2C Vo2

(C) 4C Vo2

(D) 8C Vo2

Ans: (D)

Question:3. The plates of a parallel plate charged capacitor are not parallel, the interface charge density is

(A) is higher at the closer end

(B) is non-uniform

(C) is higher at inclined plate.

(D) none of the above

Ans: (A)

Question:4. There are ‘n’ identical capacitors, which are connected in parallel to a potential difference V. These capacitors are then reconnected, in series. The potential difference between the extreme ends is :

(A) zero

(B) nV

(C) (n – 1) V

(D) none of the above

Ans: (B)

Question:5. The force with which the plates of a parallel plate capacitor having a charge Q and area of each plate A, attract each other is

(A) directly proportional to Q2 and inversely to A.

(B) inversely proportional to Q2 and directly to A.

(C) does not depend upon Q2 and is inversely proportional to A.

(D) none of the above

Ans: (A)

Question:6. The equivalent capacitance between points A and B for the given figure is (A) 1 μF

(B) 2 μF

(C) 3 μF

(D) 4 μF

Ans: (A)

Question:7. The equivalent capacitance between A and B is (A) 6 C

(B) 4C

(C) 2C

(D) none of the above

Ans: (C)

Question:8. A dielectric slab of thickness 4 mm is placed between the plates of a parallel plate capacitor. If the distance between plates is reduced by 3.5 mm, the capacity of the capacitor remains same. Find the dielectric constant of the medium.

(A) 2

(B) 4

(C) 6

(D) 8

Ans: (D)

Question:9. The effective capacitance between A and B will be (A) 0.5 μF

(B) 1.5 μF

(C) 2 μF

(D) 2.5 μF

Ans: (C)

Question:10. If the capacitance between two successive plates is C, then the capacitance of the equivalent system between A and B is (A) C/3

(B) 3C

(C) 2C/3

(D) 3C/2

Ans: (B)

Question:11. Two capacitors are once connected in parallel and then in series. If the equivalent capacitance in two cases are 16F and 3F respectively, then capacitance of each capacitor is

(A) 16 F, 3F

(B) 12 F, 4 F

(C) 6F, 8F

(D) none of these

Ans: (B)

Question:12. Two dielectrics of equal size are inserted inside a parallel plate capacitor as shown. With what factor the effective capacitance increases ? (A) $\large \frac{k_1 k_2}{k_1 + k_2}$

(B) $\large \frac{k_1 + k_2}{2}$

(C) $\large \frac{2 k_1 k_2}{k_1 + k_2}$

(D) None of these

Ans: (B)

Question:13. What is the energy stored in the capacitor between terminals a and b of the network shown in the figure? (Capacitance of each capacitor C = 5 μF). (A) 1 μJ

(B) 0.25 μJ

(C) zero.

(D) 15.6 μJ

Ans: (C)

Question:14. One of the plates of a charged parallel plate capacitor is connected to a non conducting spring of stiffness K and the other plate is fixed. The other end of the spring is also fixed. In equilibrium distance between the plates is d, which is twice of the elongation in the spring. If length of the spring is halved by cutting it, the distance between the plates in equilibrium will be (Consider that in both the cases spring is in nature length, if the capacitor is uncharged)

(A) 3d/4

(B) 5d/4

(C) 2d

(D) 3d/2

Ans: (B)

Question:15. Two identical parallel plate capacitors of same dimensions are connected to a DC source in series. When one of the plates of one capacitor is brought closer to other plate

(A) the voltage on the capacitor whose plates came closer is greater than the voltage on the capacitor whose plates are not moved.

(B) the voltage on the capacitor whose plates came closer is smaller than the voltage on the capacitor whose plates are not moved.

(C) the voltage on the two capacitors remain equal.

(D) the applied voltage is divided equally between the two capacitors.

Ans: (B)

Question:16. You are given 32 capacitors of 4 μF capacitance each. How do you connect all of them so that the effective capacitance becomes 8 μF ?

(A) 4 capacitors in series and 8 such groups in parallel.

(B) 2 capacitors in series and 16 such groups in parallel.

(C) 8 capacitors in series and 4 such groups in parallel.

(D) All of them in series.

Ans: (A)

Question:17. Figure shows a spherical capacitor with inner sphere earthed. The capacitance of the system is (A) $\large \frac{4\pi \epsilon_0 a b}{b-a}$

(B) $\large \frac{4\pi \epsilon_0 b^2}{b-a}$

(C) $\large 4\pi \epsilon_0 ( b + a )$

(D) one of these

Ans: (B)

Question:18. The charge flowing across the circuit on closing the key K is equal to (A) CV

(B) CV/2

(C) 2CV

(D) zero

Ans: (B)

Question:19. The potential difference across the capacitor of 2 μF is (A) 10 V

(B) 60 V

(C) 28 V

(D) 56 V

Ans: (B)

Question:20. What is the potential at point O ? (A) 4.27 V

(B) 17 V

(C) zero

(D) 34 V