MUET / Sukkur IBA Engineering Physics Electromagnetic Induction — Set 2

MUET / Sukkur IBA Engineering Physics Electromagnetic Induction — Set 2

1. Question 1

   Q1. The magnetic flux linked with a coil is given by ϕ = 5t² + 3t + 16. Find induced emf at t = 4 s.

   • A) 43 V
   • B) 40 V
   • C) 63 V
   • D) 83 V

   Answer: 43 V

   Explanation: Induced emf ε = -dϕ/dt = -(10t + 3) = -43 V at t = 4 s. Magnitude is 43 V.

2. Question 2

   Q2. A coil of 100 turns and area 0.1 m² is placed in a magnetic field of 0.5 T. If it's rotated by 90° in 0.1 s, find induced emf.

   • A) 5 V
   • B) 50 V
   • C) 0 V
   • D) 25 V

   Answer: 50 V

   Explanation: ε = -N(dϕ/dt) = -100 * 0.1 * 0.5 / 0.1 = 50 V.

3. Question 3

   Q3. The self-inductance of a coil is 2 H. If current changes from 0 to 2 A in 0.5 s, find induced emf.

   • A) 8 V
   • B) -8 V
   • C) 4 V
   • D) -4 V

   Answer: 8 V

   Explanation: ε = -L(dI/dt) = -2 * (2 / 0.5) = 8 V.

4. Question 4

   Q4. A coil has 500 turns and flux linkage 0.05 Wb. If current is 5 A, find self-inductance.

   • A) 5 H
   • B) 0.05 H
   • C) 50 H
   • D) 0.5 H

   Answer: 5 H

   Explanation: L = Nϕ/I = 500 * 0.05 / 5 = 5 H.

5. Question 5

   Q5. The mutual inductance between two coils is 0.1 H. If current in one coil changes at 2 A/s, find induced emf in other coil.

   • A) 0.2 V
   • B) -0.2 V
   • C) 0.1 V
   • D) -0.1 V

   Answer: 0.2 V

   Explanation: ε = -M(dI/dt) = -0.1 * 2 = 0.2 V.

6. Question 6

   Q6. A circular coil of radius 0.1 m is placed in a uniform magnetic field of 0.2 T. If it's rotated by 180° in 0.2 s, find induced emf.

   • A) 0.0628 V
   • B) 0.1256 V
   • C) 0.628 V
   • D) 1.256 V

   Answer: 0.0628 V

   Explanation: ε = -N(dϕ/dt) = -1 * π * (0.1)² * 0.2 * 2 / 0.2 = 0.1256 V.

7. Question 7

   Q7. The magnetic flux linked with a coil is ϕ = 2t³ + t² + 1. Find induced emf at t = 1 s.

   • A) 7 V
   • B) 8 V
   • C) 5 V
   • D) 6 V

   Answer: 8 V

   Explanation: ε = -dϕ/dt = -(6t² + 2t) = -8 V at t = 1 s. Magnitude is 8 V.

8. Question 8

   Q8. A coil has self-inductance 0.5 H. If current changes from 0 to 1 A in 0.2 s, find induced emf.

   • A) 2.5 V
   • B) -2.5 V
   • C) 0.5 V
   • D) -0.5 V

   Answer: 2.5 V

   Explanation: ε = -L(dI/dt) = -0.5 * (1 / 0.2) = 2.5 V.

9. Question 9

   Q9. The mutual inductance between two coils is 0.05 H. If current in one coil changes from 0 to 2 A in 0.1 s, find induced emf in other coil.

   • A) 1 V
   • B) -1 V
   • C) 0.1 V
   • D) -0.1 V

   Answer: 1 V

   Explanation: ε = -M(dI/dt) = -0.05 * (2 / 0.1) = 1 V.

10. Question 10

    Q10. A rectangular coil of area 0.2 m² is placed in a magnetic field of 0.1 T. If it's rotated by 90° in 0.2 s, find induced emf.

    • A) 0.1 V
    • B) 0.2 V
    • C) 0 V
    • D) 0.05 V

    Answer: 0.1 V

    Explanation: ε = -N(dϕ/dt) = -1 * 0.2 * 0.1 / 0.2 = 0.1 V.

11. Question 11

    Q11. The self-inductance of a coil is 1 H. If current changes from 0 to 3 A in 0.3 s, find induced emf.

    • A) 10 V
    • B) -10 V
    • C) 5 V
    • D) -5 V

    Answer: 10 V

    Explanation: ε = -L(dI/dt) = -1 * (3 / 0.3) = 10 V.

12. Question 12

    Q12. A coil has 200 turns and flux linkage 0.1 Wb. If current is 2 A, find self-inductance.

    • A) 10 H
    • B) 0.1 H
    • C) 1 H
    • D) 0.01 H

    Answer: 10 H

    Explanation: L = Nϕ/I = 200 * 0.1 / 2 = 10 H.

13. Question 13

    Q13. The magnetic flux linked with a coil is given by ϕ = t² + 2t + 1. Find induced emf at t = 2 s.

    • A) 6 V
    • B) -6 V
    • C) 4 V
    • D) -4 V

    Answer: 6 V

    Explanation: ε = -dϕ/dt = -(2t + 2) = 6 V at t = 2 s.

14. Question 14

    Q14. A coil of inductance 0.2 H is connected to a 10 V battery. If current changes at 5 A/s, find induced emf.

    • A) 1 V
    • B) -1 V
    • C) 0 V
    • D) 10 V

    Answer: 1 V

    Explanation: ε = -L(dI/dt) = -0.2 * 5 = 1 V.

15. Question 15

    Q15. The mutual inductance between two coils is 0.02 H. If current in one coil changes at 10 A/s, find induced emf in other coil.

    • A) 0.2 V
    • B) -0.2 V
    • C) 0.1 V
    • D) -0.1 V

    Answer: 0.2 V

    Explanation: ε = -M(dI/dt) = -0.02 * 10 = 0.2 V.

16. Question 16

    Q16. A circular coil of radius 0.05 m is placed in a uniform magnetic field of 0.5 T. If it's rotated by 180° in 0.1 s, find induced emf.

    • A) 0.0785 V
    • B) 0.157 V
    • C) 0.785 V
    • D) 1.57 V

    Answer: 0.0785 V

    Explanation: ε = -N(dϕ/dt) = -1 * π * (0.05)² * 0.5 * 2 / 0.1 = 0.0785 V.

17. Question 17

    Q17. The self-inductance of a coil is 0.8 H. If current changes from 0 to 4 A in 0.4 s, find induced emf.

    • A) 8 V
    • B) -8 V
    • C) 4 V
    • D) -4 V

    Answer: 8 V

    Explanation: ε = -L(dI/dt) = -0.8 * (4 / 0.4) = 8 V.

18. Question 18

    Q18. A coil has 300 turns and flux linkage 0.02 Wb. If current is 3 A, find self-inductance.

    • A) 2 H
    • B) 0.02 H
    • C) 20 H
    • D) 0.2 H

    Answer: 2 H

    Explanation: L = Nϕ/I = 300 * 0.02 / 3 = 2 H.

19. Question 19

    Q19. The magnetic flux linked with a coil is ϕ = 3t³ + 2t² + 1. Find induced emf at t = 1 s.

    • A) 13 V
    • B) 12 V
    • C) 11 V
    • D) 10 V

    Answer: 13 V

    Explanation: ε = -dϕ/dt = -(9t² + 4t) = 13 V at t = 1 s.

20. Question 20

    Q20. A coil of 100 turns is rotated at 1000 rpm in a magnetic field of 0.01 T. What is the maximum induced emf?

    • A) 10.47 V
    • B) 1.047 V
    • C) 104.7 V
    • D) 0.1047 V

    Answer: 104.7 V

    Explanation: ε = NABωsin(ωt), maximum ε = NABω = 100 * π * (0.01) * (1000/60) * 2 = 104.7 V, using ω = 2πf.