1 Physics -- Magnetic Field

Can a constant magnetic field set an electron at rest into motion? Explain.

1 Answers

In the presence of a magnetic field, a charged particle, such as an electron, experiences a force known as the Lorentz force. The Lorentz force is given by the equation:

F = q * (v x B)

where F is the force experienced by the particle, q is the charge of the particle, v is its velocity, and B is the magnetic field vector.

In this equation, the cross product (v x B) represents the direction of the force. The force is perpendicular to both the velocity vector (v) of the particle and the magnetic field vector (B). Therefore, if an electron is at rest (v = 0), the cross product (v x B) becomes zero, resulting in no force acting on the electron.

In other words, for a stationary electron, there is no velocity component to interact with the magnetic field and, consequently, no Lorentz force is exerted on it. Therefore, a constant magnetic field alone cannot set an electron at rest into motion.

If a diamagnetic substance is brought near south or north pole of a bar magnet it is a. Attracted by the poles b. Repelled by the polesc. Attracted by north pole and repelled by south pole d. Attra...

Answer is B.

What is the self - inductance of an air solenoid 50cm long and 2cm radius if it has 500 turns?

Solution:

The self-inductance is given as,

L = (µo) N² A / l

l = 50 cm = 0.5 m

r = 2cm = 0.02 m

A = pi * r^2 = pi * (0.02)^2

N = 500

Hence, L = (4 pi * 10^-7) * (500)^2 * (pi * (0.02)^2) / (0.5)

= 7.896 * 10^-4 Henry

Why the perpendicular components of the field on axis is not considered in the calculation of net magnetic field?

The perpendicular component of the magnetic field due to the upper half of the coil is cancelled due to the field produced by the lower half of the coil as both are equal in magnitude and opposite in direction.

Hence, the perpendicular components of the field on the axis are not considered in the calculation of net magnetic field.

Moving coil galvanometer is named from its construction principle. a. What is the principle of moving coil galvanometer? ...

A moving coil galvanometer is based on the principle that a current-carrying coil or loop placed in a region of a magnetic field experiences a torque.

Current sensitivity of a galvanometer defines the deflection produced in the coil per unit current supplied to the galvanometer. A high current sensitivity implies a larger deflection for each unit rise in current.

An electron is revolving in a specified orbit. Then,. a. What is magnetic field at the centre of circular path? ...

Define one ampere, halls effect, biot-savart law, Lorentz force

Explain biot-savart law with proper diagram and find its result.

Why are the pole pieces of magnets cut into cylindrical form in a galvanometer?

In a galvanometer, the pole pieces of magnets are often cut into cylindrical form to enhance the uniformity and strength of the magnetic field within the coil.

Explain why a current carrying solenoid tends to contract.

Current carrying selonoid tends to contract because when current flows through a solenoid, the currents in the various turns of the solenoid are parallel and in the same direction. Since the currents flowing through parallel wires in the same direction lead to force of attraction between them, the turns of the solenoid will also attract each other and as a result the solenoid tends to contract.

What do you mean by Hall Effect? Why is it more effective in semiconductors?

An electron beam and a proton beam are moving parallel to each other in the beginning. Do they always maintain this status? Justify your answer.

An electron beam and a proton beam, which have opposite charges, can either attract or repel each other. If the electric force between them is strong enough, they may deviate from their parallel paths and approach each other. Otherwise, they will continue to move parallel to each other.

A charged particle carrying a charge 'q' moves in an electric field E. If its specific charge is 'S', write an expression of its acceleration in terms of the above entities.

A charge particle carrying a charge q moves in an electric field 'E'. If its specific charge is 'S', then force is given as

F = qE

and acceleration, a= F/m = SE ( since, q/m= S given )

acceleration, a = SE

Under what conditions does a charge affect a magnet?

When a fast moving charge particle enter to a magnetic field as well as force is developed in the charge which is F = Bqv sinΘ, where B is magnetic field intensity, q is the charge, v is the velocity of charge particle and Θ be the angle between the velocity and magnetic fields. Due to this reason, the fast moving charge particle affect the magnet.

Does a charged particle moving through a magnetic field always experience a force? Explain.

Yes, a charged particle moving through a magnetic field always experiences a force. This force, known as the Lorentz force, is perpendicular to the particle's velocity and the magnetic field direction. It causes the particle to move in a curved path. The magnitude of the force depends on the charge, velocity, and strength of the magnetic field.

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