Electromagnetism Quiz - ICSE Class 10 Physics
Free practice quiz: Electromagnetism (ICSE Class 10 Physics). 44 multiple-choice questions with answers and explanations. Play online, no sign-up needed.
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A circular coil of radius 'R' has 'N' turns. If a current 'I' flows through the coil, what is the magnetic field at the center of the coil?
- μ₀NI / (2R)
- μ₀NI / R
- μ₀I / (2R)
- μ₀NI / (4R)
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Answer: A. μ₀NI / (2R)
The magnetic field at the center of a circular coil with N turns, radius R, carrying current I is given by the formula B = μ₀NI / (2R), where μ₀ is the permeability of free space.
A charge Q moves with velocity v in a magnetic field B. The magnetic force on the charge is zero if:
- v is parallel to B
- v is perpendicular to B
- v = 0
- Both A and C
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Answer: D. Both A and C
The magnetic force on a moving charge is given by the Lorentz force formula: F = q(v x B). The magnitude of the cross product (v x B) is |v||B|sinθ, where θ is the angle between v and B. The force is zero if sinθ = 0 (meaning v is parallel or anti-parallel to B) or if v = 0.
Faraday's law of electromagnetic induction states that the induced EMF is proportional to:
- The magnetic flux itself
- The rate of change of magnetic flux
- The magnetic field strength
- The resistance of the coil
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Answer: B. The rate of change of magnetic flux
Faraday's first law of electromagnetic induction states that the magnitude of the induced EMF in any closed circuit is equal to the rate of change of the magnetic flux through the circuit. Mathematically, ε = -dΦ/dt.
The magnetic field strength at the end of a long solenoid is:
- Half of the field at the center
- Equal to the field at the center
- Twice the field at the center
- Zero
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Answer: A. Half of the field at the center
For a long solenoid, the magnetic field is approximately uniform and equal to μ₀nI throughout its interior, except very near the ends. At the ends of a long solenoid, the magnetic field strength is approximately half the value of the magnetic field at the center.
The direction of induced current in a coil when a magnet is brought near it is such that it:
- Attracts the magnet
- Repels the magnet
- Has no effect on the magnet
- First attracts then repels the magnet
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Answer: B. Repels the magnet
According to Lenz's law, the induced current in a coil flows in a direction that opposes the change in magnetic flux causing it. When a magnet is brought near the coil, the induced current creates a magnetic field that opposes the motion of the magnet, effectively repelling it.