Q. A sinusoidal voltage of peak value 283 V and frequency 50 Hz is applied to a series LCR circuit in which R = 3 Ω, L = 25.48 mH, and C = 796 µF, then the power dissipated at the resonant condition will be- (i)39.70 kW(ii) 26.70 kW(iii)13.35 kW(iv)Zero Answer: (iii)13.35 kW Vo = […]
Q. An air-cored solenoid with length 30 cm, area of cross-section 25 cm2 and number of turns 800, carries a current of 2.5 A. The current is suddenly switched off in a brief time of 10-3s. Ignoring the variation in magnetic field near the ends of the solenoid, the average back emf induced across the
Q. In a hydrogen atom the electron moves in an orbit of radius 0.5 Ao making 10 revolutions per second, the magnetic moment associated with the orbital motion of the electron will be(i) 2.512 x 10-38 Am2(ii) 1.256 x 10-38 Am2 (iii) 0.628 X 10-38 Am2 (iv) zero Answer: (ii) 1.256 x 10-38 Am2 R
Q. Three infinitely long parallel straight current carrying wires A, B and C are kept at equal distance from each other as shown in the figure . The wire C experiences net force F .The net force on wire C, when the current in wire A is reversed will be (i) Zero(ii) F/2(iii) F(iv) 2F
Q. The current sensitivity of a galvanometer increases by 20%. If its resistance also increases by 25%, the voltage sensitivity will(i ) decrease by 1%(ii) increased by 5%(iii) increased by 10%(iv) decrease by 4% Answer: (iv) decrease by 4% Given,
Q. A 10m long wire of uniform cross-section and 20ohm resistance used in a potentiometer. This wire is connected in series with a battery of 5 V along with an external resistance of 480Ω. If an unknown e.m.f. E is balanced at 6.0m length of the wire, then the value of unknown emf is- (i)
Q. A straight line plot showing the terminal potential difference (V) of a cell as a function of current (I) drawn from it, is shown in figure. The internal resistance of the cell would be then (i) 2.8 ohms(ii) 1.4 ohms(iii) 1.2 ohms(iv) zero Answer: (i) 2.8 ohms I = 0, V = E, ∴E
Q. Three resistors having values R1, R2, and R3 are connected in series to a battery. Suppose R1 carries a current of 2.0 A, R2 has a resistance of 3.0 ohms, and R3 dissipates 6.0 watts of power. Then the voltage across R is-(i) 1V(ii) 2V(iii) 3V(iv) 4V Answer: (iii) 3V GivenI = 2 A,
Q. A battery is connected to the conductor of non-uniform cross section area. The quantities or quantity which remains constant is-(i) electric field only(ii) drift speed and electric field(iii)electric field and current(iv) current only Answer: (iv) current only Correct option is (iv), Rest all quantities change with area of cross-section of a conductor.
Q. A solid spherical conductor has charge +Q and radius R. It is surrounded by a solid spherical shell with charge -Q, innerradius 2R, and outer radius 3R. Which of the following statements is true? (i)The electric potential has a maximum magnitude at C and the electric field has a maximum magnitude at A(ii) The