HomeTestsSearchRankProfile
easyMCQPhysicsPhysics
1 mark

A beam of electrons passes un-deflected through mutually perpendicular electric and magnetic fields. If the electric field is switched off, and the same magnetic field is maintained, the electrons move:

  1. A
    in an elliptical orbit
  2. B
    in a circular orbit
  3. C
    along a parabolic path
  4. D
    along a straight line

Solution & Step-by-step Explanation

When the electric field is off, only the magnetic field acts. Since the velocity was perpendicular to the electric field and the fields were mutually perpendicular, the velocity is perpendicular to the magnetic field. A charged particle moving perpendicular to a uniform magnetic field follows a circular orbit.

Practice this question

Try it yourself before checking the explanation above.

A beam of electrons passes un-deflected through mutually perpendicular electric and magnetic fields. If the electric field is switched off, and the same magnetic field is maintained, the electrons move:
A
in an elliptical orbit
B
in a circular orbit
C
along a parabolic path
D
along a straight line

Share This Question

MagnetismLorentz Force

Related Questions

mediumMCQ

Consider a water tank as shown in the figure. It has one wall at x = L and is very wide in the z direction. When filled with a liquid of surface tension S and density ρ , the liquid surface makes an angle θ_0 ( θ_0 1 ) with the x -axis at x = L . If y(x) is the height of the surface, then the equation for y(x) is:(Take θ(x) ≈ θ(x) ≈ θ(x) = dy/dx and g as acceleration due to gravity) ![image](https://pub-7faa453bd1ec4bf0a04cc031c6f058de.r2.dev/images/e48999a7-2b29-4d5c-be16-ae2fd5fbcea5.png)

mediumMCQ

A microscope has an objective of focal length 2 cm , eyepiece of focal length 4 cm and the tube length of 40 cm . If the distance of distinct vision of eye is 25 cm , the magnification in the microscope is:

mediumMCQ

An electron (mass 9 × 10^-31 kg and charge 1.6 × 10^-19 C ) moving with speed c/100 ( c = speed of light) is injected into a magnetic field B of magnitude 9 × 10^-4 T perpendicular to its direction of motion. We wish to apply a uniform electric field E together with the magnetic field so that the electron does not deflect from its path. Then (speed of light c = 3 × 10^8 ms^-1 ):

mediumMCQ

There are two inclined surfaces of equal length ( L ) and same angle of inclination 45^ with the horizontal. One of them is rough and the other is perfectly smooth. A given body takes 2 times as much time to slide down on rough surface than on the smooth surface. The coefficient of kinetic friction ( μ_k ) between the object and the rough surface is close to:

mediumMCQ

The kinetic energies of two similar cars A and B are 100 J and 225 J respectively. On applying breaks, car A stops after 1000 m and car B stops after 1500 m . If F_A and F_B are the forces applied by the breaks on cars A and B, respectively, then the ratio F_A/F_B is:

easyMCQ

Which of the following options represents the variation of photoelectric current with intensity and frequency of light shown on the x-axis? ![image](https://pub-7faa453bd1ec4bf0a04cc031c6f058de.r2.dev/images/a9f0839b-e582-4a05-99a9-ba0021dc875f.png)

Ready for a Full Test?

Practice with timed mock tests and track your performance across Physics.

Browse TestsLeaderboard

Discussion