Practice Questions

Q21.A conducting circular loop is placed in a uniform magnetic field of 0. 4 T with its plane perpendicular to the field. Somehow, the radius of the loop starts expanding at a constant rate of 1 mm s−1 . The magnitude of induced emf in the loop at an instant when the radius of the loop is 2 cm will be _______ μV .

Q21.An electron is allowed to move with constant velocity along the axis of current carrying straight solenoid. (A) The electron will experience magnetic force along the axis of the solenoid. (B) The electron will not experience magnetic force. (C) The electron will continue to move along the axis of the solenoid. (D) The electron will be accelerated along the axis of the solenoid. (E) The electron will follow parabolic path-inside the solenoid. Choose the correct answer from the option given below: (1) B, C and D only (2) A and D only (3) B and C only (4) B and E only

Q21.A horse rider covers half the distance with 5 m s-1 speed. The remaining part of the distance was travelled with speed 10 m s-1 for half the time and with speed 15 m s-1 for other half of the time. The mean 𝑥 speed of the rider averaged over the whole time of motion is m s-1. The value of 𝑥 is ______. 7

Q21.A projectile fired at 30° to the ground is observed to be at same height at time 3 s and 5 s after projection, during its flight. The speed of projection of the projectile is m s-1. (Given 𝑔= 10 m s-2) →

Q21.An alternating voltage source V = 260 sin(628t) is connected across a pure inductor of 5 mH . Inductive reactance in the circuit is: (1) 3. 14Ω (2) 6. 28Ω (3) 0. 5Ω (4) 0. 318Ω

Q21.The speed of a swimmer is 4 km h-1 in still water. If the swimmer makes his strokes normal to the flow of river of width 1 km, he reaches a point 750 m down the stream on the opposite bank. The speed of the river water is ______ km h-1.

Q21.A small particle moves to position 5 ^𝑖- 2 ^𝑗+ ^𝑘 from its initial position 2 ^𝑖+ 3 ^𝑗- 4 ^𝑘 under the action of force 5 ^𝑖+ 2 ^𝑗+ 7 ^𝑘 N. The value of work done will be ______ J.

Q21.A metallic rod of length L is rotated with an angular speed of ω normal to a uniform magnetic field B about an axis passing through one end of rod as shown in figure. The induced emf will be : . (1) 1 B2L2ω (2) 1 BL2ω 2 4 (3) 1 BL2ω (4) 1 B2Lω 2 4

Q21.In an LC oscillator, if values of inductance and capacitance become twice and eight times, respectively, then the resonant frequency of oscillator becomes x times its initial resonant frequency ω0 . The value of x is: (1) 1/4 (2) 16 (3) 1/16 (4) 4

Q22.A solid sphere and a solid cylinder of same mass and radius are rolling on a horizontal surface without slipping. The ratio of their radius of gyrations respectively (ksph : kcyl) is 2 : √x. The value of x is _______.

Q22.A lift of mass 𝑀= 500 kg is descending with speed of 2 m s-1. Its supporting cable begins to slip thus allowing it to fall with a constant acceleration of 2 m s-2. The kinetic energy of the lift at the end of fall through to a distance of 6 m will be ______ kJ.

Q22.Two concentric circular coils with radii 1 cm and 1000 cm and number of turns 10 and 200 respectively are placed coaxially with centers coinciding. The mutual inductance of this arrangement will be _____ ×10–8 H . (Take, π2 = 10 )

Q22.A force 𝐹= 2 + 3𝑥 ^𝑖 acts on a particle in the 𝑥 direction where 𝐹 is in Newton and 𝑥 is in meter. The work done by this force during a displacement from 𝑥 = 0 to 𝑥= 4 m is _____ J.

Q22.In the given circuit, rms value of current (Irms) through the resistor R is : (1) 2 A (2) 21 A (3) 20 A (4) 2√2 A

Q22.If the earth suddenly shrinks to 1 of its original volume with its mass remaining the same, the period of 64th 24 rotation of earth becomes 𝑥ℎ. The value of 𝑥 is ________

Q22.A series LCR circuit consists of R = 80 Ω. XL = 100 Ω , and XC = 40 Ω. The input voltage is 2500 cos(100πt) V. The amplitude of current, in the circuit, is _____ A .

Q22.Which of the following Maxwell’s equation is valid for time varying conditions but not valid for static conditions: → → → → (1) (2) ∮ B ⋅ dl = μ0I ∮ E ⋅ dl = 0 −→ → → (3) ∮→D ⋅dA = Q (4) ∮ E ⋅dl = −∂ϕB∂t

Q22.A light rope is wound around a hollow cylinder of mass 5 kg and radius 70 cm. The rope is pulled with a force of 52 . 5 N. The angular acceleration of the cylinder will be _____ rad s-2.

Q22.An LCR series circuit of capacitance 62. 5 nF and resistance of 50 Ω, is connected to an A.C. source of frequency 2. 0 kHz . For maximum value of amplitude of current in circuit, the value of inductance is ____ mH . (Take π2 = 10)

Q22.A series combination of resistor of resistance 100 Ω inductor of inductance 1 H and capacitor of capacitance 6. 25 μF is connected to an ac source. The quality factor of the circuit will be _____.

Q22.Given below are two statements: Statement I : When the frequency of an AC source in a series LCR circuit increases, the current in the circuit first increases, attains a maximum value and then decreases. Statement II : In a series LCR circuit, the value of power factor at resonance is one. In the light of given statements, choose the most appropriate answer from the options given below. (1) Statement I is incorrect but Statement II is true (2) Both Statement I and Statement II are false (3) Both Statement I and Statement II are true (4) Statement I is correct but Statement II is false

Q22.Which of the following are true? A. Speed of light in vacuum is dependent on the direction of propagation. B. Speed of light in a medium is independent of the wavelength of light. C. The speed of light is independent of the motion of the source. D. The speed of light in a medium is independent of intensity. Choose the correct answer from the question given below : (1) A and C only (2) B and D only (3) B and C only (4) C and D only

Q22.An inductor of inductance 2 μH is connected in series with a resistance, a variable capacitor and an AC source of frequency 7 kHz. The value of capacitance for which maximum current is drawn into the circuit is x1 F , where the value of x is ______. (Take π = 227 )

Q22.A solid cylinder is released from rest from the top of an inclined plane of inclination 30° and length 60 cm. If the cylinder rolls without slipping, its speed upon reaching the bottom of the inclined plane is ______ m s-1. (Given 𝑔= 10 m s-2)

Q22.The magnetic intensity at the centre of a long current carrying solenoid is found to be 1. 6 × 103 A m−1 . If the number of turns is 8 per cm, then the current flowing through the solenoid is ______A.