Question

A uniform magnetic field is present in the vertically downward direction in a given region. When an electron is projected in a horizontal direction to the right, it will be moving in a circular path with constant speed 

Solution

Correct option is

Clockwise in the horizontal plane

We have . Hence v is along the x-axis, B along the

ve z-axis and q is a negative charge. Hence F is along the –ve y-axis. The electrons thus describes a horizontal circle in the x-y plane ( to the –ve z-axis, the direction of B) in the clockwise sense when viewed from above. 

 

SIMILAR QUESTIONS

Q1

When a surface is irradiated with light of wavelength 4950 Å, a photocurrent appears which vanishes if a potential greater than 0.6 V is applied across the photo-table. When a different source of light is used, it is found that the critical retarding potential is changed to 1.1 V. Find the work function of the emitting surface and the wavelength of the second source. If the photoelectrons (after emission from the surface) are subject to a magnetic field of 10 T, what changes will be observed in the above two retarding potentials? 

Q2

The maximum kinetic energy of photoelectrons emitted from a certain metallic surface is 30 eV when monochromatic radiation of wavelength  falls on it. When the sane surface is illuminated with light of wavelength , the maximum kinetic energy of photoelectrons is observed to be 10 eV. Calculate the wavelength  and determine the maximum wavelength of incident radiation for which photoelectrons can be emitted by this surface. 

Q3

A monochromatic light source of frequency v illuminates a metallic surface and ejects photoelectrons. The photoelectrons having maximum energy are just able to ionize the hydrogen atom in ground state. When the whole experiment is repeated with an incident radiation of frequency , the photoelectrons so emitted are able to excite the hydrogen atom beam which then emits a radiation of wavelength 1215Å. Find the work function of the metal and the frequency v

Q4

An electron is projected in a uniform electric field in a direction at right angles to the field. The trajectory of the electron will be   

Q5

An electron and a proton are projected in a uniform magnetic field with equal initial linear momenta in a direction perpendicular to the field. Then

Q6

An electron and a proton are projected in a uniform magnetic field with equal kinetic energies in a direction perpendicular to the field. Then  

Q7

A beam of electrons is projected with a velocity  in a region of crossed electric and magnetic fields E and B. If E = 800 Vm–1, the magnitude of B for electron beam to pass through the fields undeviated will be 

Q8

A proton (mass m, charge e), projected with a velocity v passes undeviated through a region of crossed electric and magnetic fields. With what velocity should an alpha-particle (mass 4 m, charge 2e) be projected so that it passes undeviated through the same region?  

Q9

Two electron beams having velocities in the ratio of 1 : 2 are subjected separately to identical magnetic fields. The ratio of deflections produced is 

Q10

In a cathode ray tube, the electrons are subjected to a potential difference of 182 V. The maximum speed acquired by the electrons is