Magnetic Field | MCQs

Explanation

• When a magnet is suspended freely, its north pole will point towards the Earth's magnetic South pole (which is located near the Earth's geographic North pole), and its south pole will point towards the Earth's magnetic North pole (which is located near the Earth's geographic South pole).
• This is because opposite poles attract, and the Earth's magnetic field is strong enough to align the magnet's poles.

Explanation

SQUID stands for Superconducting Quantum Interference Device.

It is an extremely sensitive magnetometer used to detect very weak magnetic fields, such as those produced by brain activity (in magnetoencephalography, or MEG).

It can detect magnetic fields as small as 10⁻¹⁴ tesla, making it ideal for brain studies.

Explanation

The unit of magnetic flux density is Wb m⁻² (weber per square meter).

It is commonly referred to as a tesla (T), which quantifies the strength of the magnetic field.

Explanation

Inside a solenoid, the magnetic field is:Uniform and directed along the axis of the solenoid.

 The field lines are parallel and evenly spaced, indicating a strong and consistent magnetic field inside the solenoid.

Explanation

When an electron moves perpendicular to a magnetic field, the electromagnetic force (also known as the Lorentz force) acting on the electron is given by the formula:

F=qvBsin(θ)

Where:

• $F$ is the force,
• $q$ is the charge of the electron,
• $v$ is the velocity of the electron,
• $B$ is the magnetic field strength,
• $$θtheta is the angle between the velocity vector and the magnetic field.

When the electron is moving perpendicular to the magnetic field, $theta = 90^circ$ and $sin(90^circ) = 1$

Therefore, the force becomes:

$$F=qvB$$

This means the force is at its maximum value since both the charge and the velocity contribute to the force. Thus, the statement that the force acting is maximum is correct.

Explanation

The strength of the magnetic field around a conductor is determined by how much current is flowing.

The magnetic field is directly proportional to the current.

Explanation

A magnetic bar has two poles: the North pole and the South pole.

These poles determine the direction of the magnetic field.

Explanation

Explanation

• Substances with permeability less than that of free space (μ₀) are called diamagnetic materials.
• These materials are weakly repelled by magnetic fields and have a relative permeability (μr) less than 1.

Explanation

• Fleming's left-hand rule correlates to current, magnetic field and direction of force on a conductor.
• This rule states that if the thumb, forefinger and middle finger of the left hand are stretched to be perpendicular to each other, and if the forefinger represents the direction of the magnetic field, the middle finger represents the direction of the current, then the thumb represents the direction of force.