De-Broglie Wave Or Matter Wave ,Davisson-Geremer Experiment (JEE LEVEL)

1.

A photon of frequency v has a momentum associated with it. If c is the velocity of light, this momentum is

(a) \frac{{hv}}{{{{c}^{\mathbf{2}}}}}

(b) \frac{{hv}}{c}

(c) \frac{v}{c}

(d) hvc

Ans (b)

2.

The de Broglie wavelength of thermal neutrons at ordinary temperature T K is

(a) \frac{{30.8}}{{\sqrt{T}}}\text{{ }\!\!\mathrm{\AA}\!\!\text{ }}    

(b) \frac{{28.7}}{{\sqrt{T}}}\text{{ }\!\!\mathrm{\AA}\!\!\text{ }}    

(c) \frac{{10.1}}{{\sqrt{T}}}\text{{ }\!\!\mathrm{\AA}\!\!\text{ }}    

(d) \frac{{20.2}}{{\sqrt{T}}}\text{{ }\!\!\mathrm{\AA}\!\!\text{ }}\text{.}

Ans  (a)

3.

The momentum of an X-ray photon of wavelength 0.10 nm will be

(a) 6.62 x 10^-34 kg-m/s                                                                       

(b) 3.31 x 10^-24 kg-m/s

(c) 3.31 x 10^-34 kg-m/s                                                                       

(d) 6.62 x 10^-24 kg-m/s

Ans (d)

4.

If E₁, E₂ and E₃ are there respective kinetic energies of an electron, an alpha particle and a proton each having the same de Broglie wavelength, then

(a) {{E}_{1}}>{{E}_{3}}>{{E}_{2}}                   

(b) {{E}_{2}}>{{E}_{3}}>{{E}_{1}}                  

(c) {{E}_{1}}>{{E}_{2}}>{{E}_{3}}                   

(d) {{E}_{1}}={{E}_{2}}={{E}_{3}}.

Ans (a)

5.

The de Broglie wavelength of an atom of mass m at absolute temperature T is

(a) \frac{h}{{mkT}}                              

(b) \frac{h}{{\sqrt{{2mkT}}}}              

(c) \frac{h}{{\sqrt{{3mkT}}}}              

(d) \frac{h}{{3mkT}}.

Ans (c)