Note: The symbols used have their standard meanings. ‘^’ indicates raised to the power. Answers are provided at the end of the post. All questions are based on the NCERT standard syllabus and are crucial for the NEET-UG examination. Special hints are provided where necessary. This serves as a mock test, so ensure thorough revision before attempting the questions.
Electromagnetic Induction Questions:
Q1) The magnetic flux linked to a circular coil with a radius R is given by 2t. What is the magnitude of the induced emf in the coil at t = 5 s?
A) 192 V B) 108 V C) 197 V D) 150 V
Q2) A square loop with a side length of 1 m and resistance 1 is placed in a magnetic field of 0.5 T. If the plane of the loop is perpendicular to the direction of the magnetic field, what is the magnetic flux through the loop?
A) 1 weber B) Zero weber C) 2 weber D) 0.5 weber
Q3) A large circular coil with 1000 turns and an average radius of 10 m is rotating about its horizontal diameter at 2 rad/s. If the vertical component of the Earth’s magnetic field at that place is 2 * 10 T and the electrical resistance of the coil is 12.56, what is the maximum induced current in the coil?
A) 1 A B) 2 A C) 0.25 A D) 1.5 A
Q4) Two conducting circular loops of radii R and R are placed in the same plane with their centers coinciding. If R >> R, the mutual inductance M between them will be directly proportional to:
A)
Q5) A wheel with 20 metallic spokes, each 1 m long, is rotated with a speed of 120 rpm in a plane perpendicular to a magnetic field of 0.4 G. What is the induced emf between the axle and the rim of the wheel? (1 G = 10 T)
A) 2.51 V B) 2.51 * 10 C) 2.51 * 10
Q6) The magnetic flux linked with a coil (in Wb) is given by the equation. What is the magnitude of the induced emf in the coil at the fourth second?
A) 10 V B) 33 V C) 43 V D) 108 V
Q7) A cycle wheel with a radius of 0.5 m is rotated with a constant angular velocity of 10 rad/s in a region of a magnetic field of 0.1 T, which is perpendicular to the plane of the wheel. What is the emf generated between its center and the rim?
A) Zero B) 0.25 V C) 0.125 V D) 0.5 V
Q8) In which of the following devices is the eddy current effect not used?
A) Induction Furnace B) Magnetic braking in Train C) Electromagnet D) Electric Heater
Q9) A 800-turn coil of effective area 0.05 m is kept perpendicular to a magnetic field 5 * 10 T. When the plane of the coil is rotated by 90 degrees around any of its coplanar axes in 0.1 s, what is the emf induced in the coil?
A) 2 V B) 0.2 V C) 2 * 10 V D) 0.02 V
Q10) A thin diamagnetic rod is placed vertically between the poles of an electromagnet. When the current in the electromagnet is switched on, the diamagnetic rod is pushed up, out of the horizontal magnetic field, gaining gravitational potential energy. Where does the work required to do this come from?
A) The current source B) The magnetic field C) The induced electric field due to the changing magnetic field D) The lattice structure of the material of the rod
Q11) The magnetic potential energy stored in a certain inductor is 25 mJ when the current in the inductor is 60 mA. What is the inductance of the inductor?
A) 0.138 H B) 138.88 H C) 13.89 H D) 1.389 H
Q12) A uniform magnetic field is restricted within a region of radius r. The magnetic field changes with time at a rate dB/dt. Loop 1 of radius R > r encloses the region r, and loop 2 of radius R is outside the region of the magnetic field. What is the emf generated?
A) Zero in loop 1 and zero in loop 2 B)
Q13) A long solenoid has 1000 turns. When a current of 4 A flows through it, the magnetic flux linked with each turn of the solenoid is 4 * 10 Wb. What is the self-inductance of the solenoid?
A) 1 H B) 4 H C) 3 H D) 2 H
Q14) An electron moves on a straight line path XY. The abcd is a coil adjacent to the path of the electron. What will be the direction of current, if any, induced in the coil?
A) No current induced B) abcd C) adcb D) The current will reverse its direction as the electron goes past the coil
Q15) A conducting square frame of side a and a long straight wire carrying current I are located in the same plane. The frame moves to the right with a constant velocity V. What is the emf induced in the frame?
Q16) A thin semicircular conducting ring (PQR) of radius r is falling with its plane vertical in a horizontal magnetic field B. What is the potential difference developed across the ring when its speed is v?
A) Zero B) Bv
Q17) A coil of self-inductance L is connected in series with a bulb B and an AC source. The brightness of the bulb decreases when:
A) Number of turns in the coil is reduced B) A capacitance of reactance X = X is included in the same circuit C) An iron rod is inserted in the coil D) Frequency of the AC source is decreased
Q18) A wire loop is rotated in a magnetic field. How many times per revolution does the frequency of change of direction of the induced emf occur?
A) Twice per revolution B) Four times per revolution C) Six times per revolution D) Once per revolution
Q19) A coil of resistance 400 is placed in a magnetic field. If the magnetic flux (Wb) linked with the coil varies with time t (s) as . What is the current in the coil at t = 2 s?
A) 2 A B) 1 A C) 0.5 A D) 0.1 A
Q20) The current (I) in the inductance is varying with time according to the plot shown in the figure. What is the correct variation of voltage with time in the coil?
A)
Q21) In a coil of resistance of 10 Ω, the induced current developed by changing magnetic flux through it is shown in the given figure as a function of time. What is the magnitude of change in flux through the coil in Weber?
A) 8 B) 2 C) 6 D) 4
Q22) The current i in a coil varies with time as shown in the given figure. What would be the variation of induced emf with time?
A)
Q23) A conducting circular loop is placed in a uniform magnetic field, B = 0.025 T, with its plane perpendicular to the loop. The radius of the loop is made to shrink at a constant rate of 1 mm/s. What is the induced emf when the radius is 2 cm?
A) 2π μV B) π μV C) π/2 μV D) 2 μV
Q24) A conducting circular loop is placed in a uniform magnetic field of 0.04 T with its plane perpendicular to the magnetic field. The radius of the loop starts shrinking at 2 mm/s. What is the induced emf in the loop when the radius is 2 cm?
A) 4.8π μV B) 0.8π μV C) 1.6π μV D) 3.2π μV
Q25) A rectangular, a square, a circular, and an elliptical loop, all in the (x-y) plane, are moving out of a uniform magnetic field with constant velocity v = v (directed along positive x-axis). The magnetic field is directed along the negative z-axis direction. During the passage of these loops out of the field region, which loop(s) will not have constant induced emf?
A) Any of the four loops B) The rectangular, circular, and elliptical loops C) The circular and elliptical loops D) Only the elliptical loop
Q26) A circular disc of radius 0.2 m is placed in a uniform magnetic field of induction 1/π (Wb/m2) in such a way that its axis makes an angle of 60 degrees with B. What is the magnetic flux linked with the disc?
A) 0.01 Wb B) 0.02 Wb C) 0.06 Wb D) 0.08 Wb
Q27) A long solenoid has 500 turns. When a current of 2 A is passed through it, the resulting magnetic flux linked with each turn of the solenoid is 4 * 10-3 Wb. What is the self-inductance of the solenoid?
A) 4.0 H B) 2.5 H C) 2.0 H D) 1.0 H
Q28) What is the value of inductance L for which the current is maximum in a series LCR circuit with C = 10 μF and ω = 1000 s-1?
A) 10 mH B) 100 mH C) 1 mH D) Cannot be calculated unless R is known
Q29) Two coils of self-inductance 2 mH and 8 mH are placed so close together that the effective flux in one coil is completely linked with the other. What is the mutual inductance between these coils?
A) 10 mH B) 6 mH C) 4 mH D) 16 mH
Answers:
Q1) (A) Q2) (D) Q3) (A) Q4) (A) Q5) (B) Q6) (C) Q7) (C) Q8) (3,4) Q9) (D) Q10) (C) Q11) (C) Q12) (D) Q13) (A) Q14) (D) Q15) (A) Q16) (D) Q17) (C) Q18) (A) Q19) (C) Q20) (B)
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