Which of the following figures represent the variation of the particle momentum and the associated de-Broglie wavelength?

1. 

2. 

3. 

4. 

 

Light with an energy flux of 25 × 10⁴ Wm^–2 falls on a perfectly reflecting surface at normal incidence. If the surface area is 15 cm², the average force exerted on the surface is :

1. $1.25\times {10}^{-6}N$

2. $2.50\times {10}^{-6}N$

3. $1.20\times {10}^{-6}N$

4. $3.0\times {10}^{-6}N$

When the energy of the incident radiation is increased by 20%, the kinetic energy of the photoelectrons emitted from a metal surface increased from emitted 0.5 eV to 0.8eV. The work function of the metal is :

1. 0.65 eV

2. 1.0 eV

3. 1.3 eV

4. 1.5 eV

If the kinetic energy of the particle is increased to 16 times its previous value, the percentage change in the de-Broglie wavelength of the particle is :

1. 25

2. 75

3. 60

4. 50

An $\mathrm{\alpha }$-particle moves in a circular path of radius 0.83 cm in the presence of a magnetic field of 0.25 Wb/m². The de-Broglie wavelength associated with the particle will be :

$1. 1 \stackrel{\mathrm{o}}{\mathrm{A}}$
$2. 0.1 \stackrel{\mathrm{o}}{\mathrm{A}}$
$3. 10 \stackrel{\mathrm{o}}{\mathrm{A}}$
$4. 0.01 \stackrel{\mathrm{o}}{\mathrm{A}}$

In the Davison and Germer experiment, the velocity of electrons emitted from the electron gun can be increased by

1.  increasing the filament current

2.  decreasing the filament current

3.  decreasing the potential difference between the anode and filament

4.  increasing the potential difference between the anode and filament

A radioactive nucleus of mass M emits a photon of frequency $\nu$ and the nucleus will recoil. The recoil energy will be

1.  $\frac{{\mathrm{h}}^2{\mathrm{\nu }}^2}{2{\mathrm{Mc}}^2}$

2.  zero

3.  $\frac{\mathrm{h\nu }}{\mathrm{c}\sqrt{2\mathrm{M}}}$

4.  $\frac{\mathrm{c}\sqrt{2\mathrm{M}}}{\mathrm{h\nu }}$