Q1. A coil of wire has 100 turns and is placed in a magnetic field of strength 0.5 T. If the area of the coil is 0.1 m², what is the maximum magnetic flux through the coil? (2022)
Solution:
Magnetic flux (Φ) = B × A × N = 0.5 T × 0.1 m² × 100 = 5 Wb.
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Q2. A solenoid has a length of 1 m and a cross-sectional area of 0.01 m². If the magnetic field inside the solenoid is 0.2 T, what is the magnetic flux through one turn of the solenoid?
Solution:
Magnetic flux (Φ) = B * A = 0.2 T * 0.01 m² = 0.002 Wb. For one turn, the flux is 0.002 Wb.
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Q3. If the area of a loop in a magnetic field is doubled while keeping the magnetic field strength constant, what happens to the magnetic flux through the loop?
Solution:
Magnetic flux (Φ) is given by Φ = B * A. If the area (A) is doubled and the magnetic field (B) remains constant, the magnetic flux also doubles.
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Q4. A coil of wire has 100 turns and is placed in a magnetic field of strength 0.5 T. If the area of the coil is 0.1 m² and the magnetic field is perpendicular to the coil, what is the magnetic flux through the coil? (2022)
Solution:
Magnetic flux (Φ) = B × A × cos(θ). Here, B = 0.5 T, A = 0.1 m², and θ = 0° (cos(0) = 1). Thus, Φ = 0.5 T × 0.1 m² × 1 = 0.05 Wb.
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Q5. A changing magnetic field induces an electric field. This phenomenon is described by which of the following laws?
Solution:
The phenomenon of a changing magnetic field inducing an electric field is described by Faraday's law of induction.
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Q6. A transformer steps down voltage from 240 V to 120 V. If the primary coil has 100 turns, how many turns does the secondary coil have? (2023)
Solution:
Using the transformer equation Vp/Vs = Np/Ns, we have 240/120 = 100/Ns, giving Ns = 50 turns.
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Q7. If the magnetic flux through a coil changes from 0.2 Wb to 0.5 Wb in 2 seconds, what is the average induced EMF? (2021)
Solution:
Average induced EMF = -ΔΦ/Δt = -(0.5 Wb - 0.2 Wb) / 2 s = -0.15 Wb/s = 150 V.
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Q8. A coil with 100 turns has a magnetic flux of 0.02 Wb passing through it. If the flux changes to 0.01 Wb in 2 seconds, what is the induced EMF? (2022)
Q9. A loop of wire is moved into a magnetic field at a constant speed. What happens to the induced current as the loop enters the magnetic field? (2023)
Solution:
As the loop enters the magnetic field, the change in magnetic flux increases, leading to an increase in the induced current.
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Q10. A loop of wire is placed in a uniform magnetic field. If the field strength is increased, what happens to the induced current? (2023)
Solution:
If the magnetic field strength increases, the magnetic flux through the loop increases, inducing a current according to Faraday's law.
