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 general knowledge science & technology

Unit Gauss corresponds to the measure

  1. Magnetic field

  2. Magnetic flux density

  3. Magnetic field intensity

  4. None
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Gauss is the CGS unit of magnetic flux density (B field), also commonly called magnetic field in everyday usage. Magnetic field intensity (H) is measured in different units (A/m in SI). The key distinction is that flux density describes the force field's strength, while intensity describes the external field's cause.

Multiple choice

The longitudinal component of the magnetic field inside an air-filled rectangular waveguide made of a perfect electric conductor is given by the following expression:

Hz (x, y, z, t) = 0.1 cos (25$\pi$x) cos (30.3$\pi$y) x cos (12$\pi$ x 109t - $\beta$z)(A/m)

The cross-sectional dimensions of the waveguide are given as a = 0.08 m and b = 0.033 m. The mode of propagation inside the waveguide is

  1. TM12

  2. TM21

  3. TE21

  4. TE12
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Multiple choice

One faraday is equal to

  1. 69,500 coulombs

  2. 91,500 coulombs

  3. 91,400 coulombs

  4. 96,500 coulombs
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

One faraday is equal to 96,500 coulombs.

Multiple choice

A rod of length 1 m aligned in east-west direction falls vertically downward at a constant speed of 72 km/h at a place where the vertical component of the Earth's magnetic field is 1/2 √3 gauss and angle of dip 300. Find the potential difference between two ends of the rod.

  1. 0.0069 x 10-4 V

  2. 10-3 V

  3. 36 x 10-4 V

  4. 40 x 104 V

  5. 0.025 x 10-4 V
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Length of rod l = 1 m,  Speed v = 72 km/h = 20 m/s, Angle of dip δ = 300. A rod falling vertically along east-west direction cuts only the horizontal component of the earth's field. Vertical component of earth's field Bv = 1/2 √3 gauss = (1/2 √3) x 10- 4 T. Horizontal component of earth's field BH = Bv / tan δ = (1/2 √3)/(1 / √3) gauss = 0.5 x 10-4 T.  So, the potential difference between the ends of is ε = BHvl = 0.5 x 10- 4 x 20 x 1 = 10- 3 V

Multiple choice

Two bar magnets A and B are freely suspended from heights of 5 feet and 8 feet, respectively. After a few rotations, they both come to rest. Choose the alternative that depicts the correct directions of alignment of the two magnets.

  1. A: North-South
    B: East-West

  2. A: North-South
    B: North-South

  3. A: East-West
    B: East-West

  4. A: East-West
    B: North-South

  5. Depends on the speed of rotation
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Yes, it is the correct answer. 

Multiple choice

The unit for intensity of magnetic induction field is

  1. N/Am

  2. Tesla

  3. Wb/

  4. All above
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

4   One tesla is defined as the field intensity generating one newton of force per ampere of current per meter of conductor. Equivalently, one tesla represents a magnetic flux density of one weber per square meter of area.

Multiple choice

A particle which does not show acceleration in a magnetic field is:

  1. alpha radiation

  2. positron

  3. gamma radiation

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

Gamma rays are high-energy photons with a very short wavelength (0.0005 to 0.1 nm). The emission of gamma radiation results from an energy change within the atomic nucleus. Gamma emission changes neither the atomic number nor the atomic mass so, they do not show acceleration in a magnetic field.