Physics

Magnetism and Magnetic Effects

230 Questions

Magnetism and magnetic effects focus on the forces exerted by magnetic fields on moving charges and magnetic materials. Questions cover magnetic dipoles, flux density, the motion of charged particles, and electromagnetic relationships. It is a vital physics topic for government competitive exams.

Magnetic dipolesCharged particle motionMagnetic flux densityBar magnetsEarth magnetism

Magnetism and Magnetic Effects Questions

Multiple choice force and torque on a current carrying rectangular loop in a uniform magnetic field torque on current carrying loop force on current carrying conductor magnetic effects of current and magnetism physics

A uniform horizontal magnetic field of $7.5\times 10^{-2}$T is set up at angle of $30^o$ with the axis of an solenoid and the magnetic moment associated with it is $1.28$J $T^{-1}$. Then the torque on it is?

  1. $4.8\times 10^{-2}$N m
  2. $1.6\times 10^{-2}$N m
  3. $1.2\times 10^{-2}$N m
  4. $4.8\times 10^{-4}$N m
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Torque, $\tau =MB\sin\theta$
Here, $M=1.28J$ $T^{-1}$, $B=7.5\times 10^{-2}T, \theta =30^o$
$\therefore \tau =1.28\times 7.5\times 10^{-2}\sin 30^o$
$=1.28\times 7.5\times 10^{-2}\times \dfrac{1}{2}$
$=0.64\times 7.5\times 10^{-2}=4.8\times 10^{-2}$N m.

Multiple choice physics electromagnetic waves properties and uses of different radiation electromagnetic spectrum spectrum

The magnetic field in a plane electromagnetic wave is given by $=2\times10^{-7} \sin(0.5\times 10^3 x+1.5\times10^{11}t)$. This electromagnetic wave is

  1. Visible light

  2. Infrared

  3. Microwave

  4. Radiowave
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The magnetic field in a plane of electromagnetic  wave is given by

$B=2\times 10^{-7}sin(0.5\times 10^3x+1.5\times 10^{11}t)$
from the above, $K=0.5\times 10^3=$ propagation constant
$K=\dfrac{2\pi}{\lambda}$ where, $\lambda=$ wavelength of wave
$\lambda=\dfrac{2\times 3.14}{0.3\times 10^3}$
$\lambda=1.256\times 10^{-2}m$
$\lambda=1.256 cm$
The electromagnetic wave is Microwave radiation in spectrum.

Multiple choice physics electromagnetic waves properties and uses of different radiation electromagnetic spectrum spectrum

In the EM wave , the amplitude of magnetic field $ H _o $ and the amplitude of electric field $ E _o $ at a place D are related as:

  1. $ H _o = E _o $
  2. $ H _ o=\frac { E _ o }{ c } $
  3. $ H _ o=\quad E _ o\quad \sqrt { \frac { \mu _ o }{ \varepsilon _ o } } $
  4. $ H _ o=\quad E _ o\quad \sqrt { \frac { \varepsilon _ o }{ \mu _ o } } $
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

In an electromagnetic wave, the relationship between the amplitudes of the electric field E0 and the magnetic field H0 is H0 = E0 * sqrt(epsilon / mu).

Multiple choice

What is the magnetic field strength of a typical neutron star?

  1. 10^8-10^9 Gauss

  2. 10^10-10^11 Gauss

  3. 10^12-10^13 Gauss

  4. 10^14-10^15 Gauss
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Neutron stars possess incredibly strong magnetic fields, typically ranging from 10^12 to 10^13 Gauss. These magnetic fields are generated by the motion of charged particles within the star's interior.

Multiple choice

What is the name of the process by which charged particles interact with magnetic fields, resulting in the formation of spiral trajectories?

  1. Synchrotron Radiation

  2. Bremsstrahlung

  3. Coulomb Scattering

  4. Inverse Compton Scattering
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Synchrotron radiation is emitted by high-energy electrons spiraling in a magnetic field, resulting in the formation of spiral trajectories.

Multiple choice

What is the ion gyroradius?

  1. The radius of the circular orbit of an ion in a magnetic field

  2. The radius of the elliptical orbit of an ion in a magnetic field

  3. The radius of the helical orbit of an ion in a magnetic field

  4. The radius of the random walk of an ion in a magnetic field
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The ion gyroradius is the radius of the circular orbit of an ion in a magnetic field. It is given by the following equation: ( r_i = \frac{m_i v_i}{q_i B} ), where ( m_i ) is the mass of the ion, ( v_i ) is the velocity of the ion, ( q_i ) is the charge of the ion, and ( B ) is the magnetic field strength.

Multiple choice

What is the electron gyroradius?

  1. The radius of the circular orbit of an electron in a magnetic field

  2. The radius of the elliptical orbit of an electron in a magnetic field

  3. The radius of the helical orbit of an electron in a magnetic field

  4. The radius of the random walk of an electron in a magnetic field
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The electron gyroradius is the radius of the circular orbit of an electron in a magnetic field. It is given by the following equation: ( r_e = \frac{m_e v_e}{e B} ), where ( m_e ) is the mass of the electron, ( v_e ) is the velocity of the electron, ( e ) is the elementary charge, and ( B ) is the magnetic field strength.

Multiple choice

What is the magnetic permeability of a vacuum?

  1. 1

  2. 0

  3. 4π x 10^-7 T m/A

  4. 8.85 x 10^-12 F/m
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The magnetic permeability of a vacuum is a constant, denoted by the symbol μ0, and its value is approximately 4π x 10^-7 T m/A.

Multiple choice

What is the magnetic field strength of a neutron star?

  1. 10^8 - 10^12 Tesla

  2. 10^4 - 10^6 Tesla

  3. 10^2 - 10^4 Tesla

  4. 10^0 - 10^2 Tesla
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Neutron stars possess incredibly strong magnetic fields, ranging from 10^8 to 10^12 Tesla. These magnetic fields are generated by the rapid rotation of the star and the movement of charged particles within its interior.

Multiple choice

What is the name of the radiation emitted by electrons spiraling in a magnetic field?

  1. Cyclotron Radiation

  2. Synchrotron Radiation

  3. Cherenkov Radiation

  4. Bremsstrahlung Radiation
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Cyclotron radiation is emitted by electrons spiraling in a magnetic field. The frequency of this radiation is equal to the cyclotron frequency, which is determined by the strength of the magnetic field and the mass and charge of the electron.

Multiple choice

What is the magnetic field intensity (H) in a region of space?

  1. The force per unit charge on a stationary charge.

  2. The force per unit current on a moving charge.

  3. The force per unit magnetic pole strength.

  4. The force per unit magnetic moment.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Magnetic field intensity (H) is defined as the force per unit current on a moving charge.

Multiple choice

What is the relationship between magnetic field intensity (H) and magnetic flux density (B) in a material?

  1. H = B

  2. H = B/μ

  3. H = μB

  4. H = μ/B
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The relationship between magnetic field intensity (H) and magnetic flux density (B) in a material is given by H = B/μ, where μ is the permeability of the material.

Multiple choice

What is the relationship between magnetic flux density (B) and magnetic field intensity (H) in a vacuum?

  1. B = H

  2. B = H/μ

  3. B = μH

  4. B = μ/H
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

In a vacuum, the relationship between magnetic flux density (B) and magnetic field intensity (H) is given by B = μH, where μ is the permeability of vacuum.

Multiple choice

What is the name of the acceleration mechanism that occurs when charged particles are accelerated by the electric field of a parallel electric and magnetic field?

  1. Fermi acceleration

  2. Shock acceleration

  3. Magnetic reconnection

  4. Betatron acceleration
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Betatron acceleration is the acceleration mechanism that occurs when charged particles are accelerated by the electric field of a parallel electric and magnetic field. It is a common mechanism for particle acceleration in astrophysical environments, such as the Earth's radiation belts and the solar wind.

Multiple choice

What is the magnetic field strength of a neutron star?

  1. 10^8 - 10^12 Gauss

  2. 10^4 - 10^8 Gauss

  3. 10^2 - 10^4 Gauss

  4. 10 - 10^2 Gauss
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Neutron stars possess extremely strong magnetic fields, ranging from 10^8 to 10^12 Gauss. These magnetic fields are generated by the rapid rotation of the star and the movement of charged particles within it.