1

Electron beams are accelerated to potentials 40 kV and 150 V. Estimate the wavelengths of the electrons in the two beams.

Hots Questions

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1

Electron beams are accelerated to potentials 40 kV and 150 V. Estimate the wavelengths of the electrons in the two beams.

2

An excited electron gets relieved of its excess energy by emitting one or more photons of characteristic frequency. Find the uncertainity in the frequency of the radiation if the average period that elapses between the excitation of the atom and the time of radiation is $10_{−8}$ second.

3

A proton is confined to a nucleus of radius, $5×10_{−5}$ m. Calculate the minimum uncertainity in its momentum. Also calculate the minimum kinetic energy the proton should have. The proton mass is $6.67×10_{−27}$ kg.

4

In a Dempster mass spectrograph, a 1000 V accelerating potential brings Mg

on a slit. Calculate the potential required to bring Mg on the slit, the magnetic field being held constant.

5

In a photocell the plates P and Q have a separation of 5 cm which are connected through a galvanometer without any cell. Bichromatic light of wavelengths 4000 $A_{0}$ and 6000 $A_{0}$ are incident on plate Q whose work function is 2.39 eV. If a uniform magnetic field B exists parallel to the plates, find the minimum value for B for which the galvanometer shows zero deflection.