Tiêu đề 2.ELECTROSTATIC POTENTIAL AND CAPACITANCE - Questions.pdf ✅

2.ELECTROSTATIC POTENTIAL AND CAPACITANCE (1.)Two positive point charges of 12 μ C and 8 μC are placed 10 cm, apart in air. The work done to bring them 4 cm closer is (a.) Zero (b.) 3.5 J (c.) 4.8 J (d.) 5.8 J (2.)Two thin wire rings each having a radius R are placed at a distance d apart with their axes coinciding. The charges on the two rings are +q and –q. The potential difference between the centres of two rings is (a.) qR 4πε0d2 (b.) q 2πε0 [ 1 R − 1 √R2+d2 ] (c.) Zero (d.) q 4πε0 [ 1 R − 1 √R2+d2 ] (3.)4 point charges each +q is placed on the circumference of a circle of diameter 2d in such a way that they form a square. The potential at the centre is (a.) 0 (b.) 4q d (c.) 4d q (d.) q 4d (4.)An infinite line charge produces a field of 9 × 104 NC −1 at a distance of 2 cm. the linear density is (a.) 2 × 10−7 Cm−1 (b.) 10−7 Cm−1 (c.) 9 × 104 Cm−1 (d.) None of these (5.)The voltage of clouds is 4 × 106V with respect to ground. In a lightning strike lasting 100ms, a charge of 4C is delivered to the ground. The power of lightning strike is (a.) 160 MW (b.) 80 MW (c.) 20 MW (d.) 500 kW (6.)Two parallel plates of area A are separated by two different dielectric as shown in figure. The net capacitance is (a.) ε0A 2d (b.) ε0A d (c.) 3ε0A d (d.) 4ε0A 3d (7.)What is the potential difference across 2μF capacitor in the circuit shown? (a.) 12 V (b.) 4 V (c.) 6 V (d.) 18 V (8.)The maximum field intensity on the axis of a uniformly charged ring of charge q and radius R will be (a.) 1 4πε0 . q 3√3R2 (b.) 1 4πε0 . 2q 3R2 (c.) 1 4πε0 . 2q 3√3R2 (d.) 1 4πε0 . 3q 3√3R2 (9.)The equivalent capacitance of the combination of the capacitors is
(a.) 3.20 μF (b.) 7.80 μF (c.) 3.90 μF (d.) 2.16 μF (10.)The electric potential V at any point x, y, z (all the metre) in space is given by V = 4x 2 volt. The electric field at the point (1m, 0, 2m) in Vm−1 is (a.) −8i̇ ̂ (b.) +8i̇ ̂ (c.) −16i̇ ̂ (d.) 16k̂ (11.)ABCD is a rectangle. At corners B, C and D of the rectangle are placed charges +10 × 10−10C, −20 × 10−12C, and 10 × 10−12C, respectively. Calculate the potential at the fourth corner. (The side AB=4cm and BC=3cm) (a.) 1.65 V (b.) 0.165V (c.) 16.5V (d.) 2.65V (12.)The total energy stored in the condenser system shown in the figure will be (a.) 2 μJ (b.) 4 μJ (c.) 8 μJ (d.) 16 μJ (13.)The capacitance C of a capacitor is (a.) Independent of the charge and potential of the capacitor (b.) Dependent on the charge and independent of potential (c.) Independent of the geometrical configuration of the capacitor (d.) Independent of the dielectric medium between the two conducting surface of the capacitor (14.)Two plates are 20 cm apart and the potential difference between them is 10 V. The electric field between the plates is (a.) 50 Vm−1 (b.) 500 Vm−1 (c.) 0.5 Vm−1 (d.) 20 Vm−1 (15.)Three concentric conducting spherical shells carry charges as follows :+Q on the inner shell, −2Q on the middle shell and −5 Q on the outer shell. The charge in the inner surface of the outer shell is (a.) Zero (b.) + Q (c.) −2 Q (d.) −3 Q (16.)The equivalent capacity between points A and B in figure will be, while capacitance of each capacitor is 3 μF. (a.) 2 μF (b.) 4 μF (c.) 7 μF (d.) 9 μF (17.)Two parallel large thin metal sheets have equal surface charge densities (σ = 26.4 × 10−12Cm−2 )of opposite signs. The electric field between these sheets is (a.) 1.5 NC−1 (b.) 1.5× 10−10NC−1 (c.) 3 NC−1 (d.) 3 × 10−10 NC−1 (18.)Two identical capacitors have the same capacitanceC. One of them is charged to potential V1 and the other toV2. The negative ends of the capacitors are connected together. When the positive ends are also connected, the decrease in energy of the system is (a.) 1 4 C(V1 2 − V2 2 ) (b.) 1 4 C(V1 2 + V2 2 ) (c.) 1 4 C(V1 − V2 ) 2 (d.) 1 4 C(V1 + V2 ) 2 (19.)Find the potential at the centre of a square of side √2m. Which carries at its four corners charges q1 = 3 × 10−6C,q2 = −3 × 10−6C, q3=−4 × 10−6C, q4 = 7 × 10−6C (a.) 2.7 × 104V (b.) 1.5 × 103V (c.) 3 × 102V (d.) 5 × 103V (20.)A parallel plate capacitor is made by stocking n equally spaced plates connected alternately. If the capacitance between any two plates is x, then the total capacitance is, (a.) nx (b.) n/x (c.) nx 2 (d.) (n − 1)x (21.)The work done in moving an alpha particle between two points having potential difference 25 V is A B d
(a.) 8 × 10−18J (b.) 8 × 10−19J (c.) 8 × 10−20J (d.) 8 × 10−16J (22.)A capacitor is charged to store an energy U. the charging battery is disconnected. An identical capacitor is now connected to the first capacitor in parallel. The energy in each of the capacitor is (a.) 3 U/2 (b.) U (c.) U/4 (d.) U/2 (23.)A capacitor of capacitance 1 μF is filled with two dielectrics of dielectric constant 4 and 6. What is the new capacitance? (a.) 10 μF (b.) 5 μF (c.) 4 μF (d.) 7 μF (24.)The potential energy of system of two equal negative point charges of 2μC each held 1m apart in air is (k = 9 × 109 SI unit) (a.) 36J (b.) 3.6 × 10−3 J (c.) 3.6J (d.) 3.6 × 10−2 J (25.)A 500 μF capacitor is charged at a steady rate of 100μCs−1 . The potential difference across the capacitor will be 10 V after in interval of (a.) 5 s (b.) 25 s (c.) 20 s (d.) 50 s (26.)An uncharged sphere of metal is placed inside a charged parallel plate capacitor. The lines of force will look like (a.) (b.) (c.) (d.) (27.)A hollow metal sphere of radius 5 cm is charged such that potential at its surface is 10V. The potential at the centre of the sphere is (a.) Zero (b.) 10 V (c.) Same as at point 5cm away from the surface (d.) Same as at point 10cm away from the surface (28.)Potential energy of two equal negative point charges 2μC each held 1 m apart in air is (a.) 2 J (b.) 2 eV (c.) 4 J (d.) 0.036 J (29.)Consider the charge configuration and a spherical Gaussian surface as shown in the figure. When calculating the flux of the electric field over the spherical surface, the electric field will be due to (a.) q2 (b.) Only the positive charge (c.) All the charges (d.) +q1 and −q1 (30.)Two metal pieces having a potential difference of 800 V are 0.2 m apart horizontally. A particle of mass 1.96 × 10−15kg is suspended in equilibrium between the plates. If e is an elementary charge, then charge on the particle is (a.) 8 e (b.) 6 e (c.) 3 e (d.) e (31.)The four capacitors, each of 25 μF are connected as shown in figure. The DC voltmeter reads 200 V. the change on each plate of capacitor is