Question 2 :
The energy of a $K$-electron in tungsten is $-20keV$ and of an $L$-electrons is $-2keV$. The wavelength of X-rays emitted when there is electron jump from $L$ to $K$ shell:

Question 3 :
A proton when accelerated through a potential difference of &#160;V volt&#160;has a wavelength $\lambda $ associated with it. An $\alpha&#160; $ -&#160;particle in order to have the same wavelength $\lambda $&#160;must be accelerated through a p.d. of<br/>

Question 4 :
The de-Broglie wavelength associated with with the particle of mass $m$ moving with velocity $v$ is&#160;

Question 6 :
For the same kinetic energy, the momentum shall be minimum for

Question 7 :
By means of the diffraction experiment, it is determined that the electron's de Broglie wavelength is $6.6 \times {10}^{-10} m$.&#160;What is the electron's linear momentum? Use Planck's constant,&#160;$h =&#160;6.6 \times {10}^{-34} J{A} s$.<br/>

Question 8 :
If h is Plancks constant, the momentum&#160;of a photon of wavelength 0.01 $A^o$ is

Question 9 :
Moving with the same velocity, one of the following&#160;has the longest de Broglie wavelength<br/>

Question 10 :
If the mass of a microscopic particle a well as its speed are halved, the de-broglie wavelength associated with the particle will

Question 11 :
The minimum frequency of light source to get&#160;photocurrent, from a metal surface having work&#160;function 2eV is<br/>

Question 13 :
Considerthe four gases hydrogen, oxygen, nitrogen and helium at the same temperature.Arrange them in the increasing order of the de Broglie wavelengths of theirmolecules.

Question 14 :
An&#160;electromagnetic wave of wavelength $\lambda$ is incident on a photosensitive&#160;surface of negligible work function. If the photoelectrons emitted from this&#160;surface have the de Brogue wavelength $\lambda'$, then&#160;

Question 15 :
Two electrons are moving with non-relativistic speeds perpendicular to each other. If corresponding de Broglie wavelengths are ${ \lambda }_{ 1 }$ and ${ \lambda }_{ 2 }$, their de Broglie wavelength in the frame of reference attached to their centre of mass is:

Question 17 :
An electron beam accelerated from rest througha potential difference of 5000V in vacuum isallowed to incident on a surface normally. Theincident current is 50mA, and if the electrons cometo rest on striking the suface, the force on it is<br>

Question 19 :
A $100$ watt bulb emits monochromatic light of wavelength $400$ nm. Calculate the number of photons emitted per second by bulb :

Question 20 :
The wave nature of particles was studied using diffraction of particle beams by crystal lattices. The wavelength of the waves associated with fast moving particles was found to be in agreement with the de Broglie relation.<br/>For a particle of mass $m$ moving with kinetic energy $E$, the de Broglie wavelength is<br/>