alleryMagnetic field is measured in:
- newton
- coulomb
- tesla
- henry
Show answer and solution
Correct answer: C. tesla
SI unit of magnetic field B is tesla (T) = 1 N/(A m) = 1 kg/(A s²).
**Old unit gauss:** 1 T = 10⁴ G. Earth's field is about 50 μT.
JEE Main Electromagnetism — practice questions
Explore 32 free Electromagnetism questions in JEE Main Physics. Open each question or exercise to read its content, reference answers and available explanation.
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Magnetic field is measured in:Read the answer and worked solution →Biot Savart law gives magnetic field due to a current element. It states dB is proportional to:Read the answer and worked solution →The magnetic force on a charge q moving with velocity v in field B:Read the answer and worked solution →A current-carrying wire of length L in magnetic field B experiences force:Read the answer and worked solution →Ampere's law states the line integral of B around a closed loop equals:Read the answer and worked solution →A magnetic dipole moment of a current loop is:Read the answer and worked solution →Magnetic field at center of a circular loop of radius R carrying current I:Read the answer and worked solution →Magnetic field inside a long solenoid (n turns per unit length, current I):Read the answer and worked solution →Magnetic field at distance r from a long straight current-carrying wire:Read the answer and worked solution →A charged particle of charge q, mass m enters magnetic field B perpendicular to velocity v. It follows a:Read the answer and worked solution →Torque on a current loop (moment m) in uniform field B:Read the answer and worked solution →In a velocity selector, electric field E and magnetic field B are perpendicular. Velocity of particles passing undeflected:Read the answer and worked solution →Magnetic field on the axis of a circular loop at distance x from center:Read the answer and worked solution →Magnetic flux through a surface is:Read the answer and worked solution →Cyclotron frequency for a charged particle in magnetic field B:Read the answer and worked solution →A solenoid of 200 turns, length 0.5 m, carries 2 A. Find magnetic field inside (μ₀ = 4π × 10⁻⁷):Read the answer and worked solution →A charged particle moves in a circle of radius 2 cm in a 1 T magnetic field with speed 4 × 10⁶ m/s. Mass-to-charge ratio m/q:Read the answer and worked solution →For a current loop in a non-uniform magnetic field, net force is zero only if:Read the answer and worked solution →Earth's magnetic field is approximately 50 μT. Force on a 1 m wire carrying 10 A perpendicular to field:Read the answer and worked solution →A toroid with 1000 turns and average radius 10 cm carries 0.5 A current. Field inside:Read the answer and worked solution →Two parallel wires carrying currents in OPPOSITE directions:Read the answer and worked solution →A magnetic dipole of moment m in field B has potential energy:Read the answer and worked solution →Coulomb's law gives the force between two point charges q₁ and q₂ separated by distance r in vacuum asRead the answer and worked solution →Two point charges of +2 μC each are placed 3 m apart in vacuum. The force between them is (k = 9 × 10⁹ N m²/C²)Read the answer and worked solution →The electric field at distance r from an isolated point charge q isRead the answer and worked solution →The electric field of an infinite line of charge with linear charge density λ at perpendicular distance r isRead the answer and worked solution →The electric field just outside a uniformly charged infinite plane with surface charge density σ isRead the answer and worked solution →Gauss's law states that the total electric flux through a closed surface equalsRead the answer and worked solution →An electric dipole consists of two equal and opposite point charges ±q separated by distance 2a. Its dipole moment magnitude isRead the answer and worked solution →The electric field on the axial line of a short electric dipole at distance r isRead the answer and worked solution →
Worked practice questions
Biot Savart law gives magnetic field due to a current element. It states dB is proportional to:
- I dl × r / r³
- I × r
- dl / r²
- I × dl
Show answer and solution
Correct answer: A. I dl × r / r³
We have dB = (μ₀ / 4π) × (I dl × r̂ / r²).
So dB = (μ₀ / 4π) × (I dl × r / r³).
Direction by right-hand rule (cross product of dl and r).
The magnetic force on a charge q moving with velocity v in field B:
- qE
- qvB sin theta
- q²B
- qB/v
Show answer and solution
Correct answer: B. qvB sin theta
F = qv × B. Magnitude F = qvB sin theta where theta is angle between v and B. Direction perpendicular to both v and B.
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