A beam of electrons is moving with constant velocity in a region having electric and magnetic fields of strength $20 {\mathrm{Vm}}^{-1}$ and 0.5 T at right angles to the direction of motion of the electrons. What is the velocity of the electrons

1. 20 ${\mathrm{ms}}^{-1}$                  2. 40 ${\mathrm{ms}}^{-1}$ 
3. 8 ${\mathrm{ms}}^{-1}$                    4. 5.5 ${\mathrm{ms}}^{-1}$

Electron volt is a unit of 
(1) Potential                         

(2) Charge

(3) Power                             

(4) Energy

The ratio of specific charge of an $\mathrm{\alpha }$-particle to that of a proton is 
(1) 2 : 1                     

(2) 1 : 1

(3) 1 : 2                     

(4) 1 : 3

In Bainbridge mass spectrograph a potential difference of 1000 V is applied between two plates distant 1 cm apart and magnetic field in B = 1T. The velocity of undeflected positive ions in m/s from the velocity selector is

(1)${10}^7 \mathrm{m}/\mathrm{s}$                    

(2) ${10}^4 \mathrm{m}/\mathrm{s}$

(3) ${10}^5 \mathrm{m}/\mathrm{s}$                   

(4) ${10}^2 \mathrm{m}/\mathrm{s}$ 

Order of q/m ratio of proton, $\alpha$-particle and electron is

(a) $\mathrm{e}>\mathrm{p}>\mathrm{\alpha }$               (b) $\mathrm{p}>\mathrm{\alpha }>\mathrm{e}$

(c) $\mathrm{e}>\mathrm{\alpha }>\mathrm{p}$               (d) None of these

${\mathrm{O}}^{++}, {\mathrm{C}}^{+}, {\mathrm{He}}^{++}$ and ${\mathrm{H}}^{+}$ ions are projected on the photographic plate with the same velocity in a mass spectrograph. Which one will strike the farthest?
1. ${\mathrm{O}}^{++}$
2. ${\mathrm{C}}^{+}$
3. ${\mathrm{He}}^{++}$
4. H⁺

In an electron gun, the electrons are accelerated by the potential V. If e is the charge and m is the mass of an electron, then the maximum velocity of these electrons will be

(1) $\frac{2\mathrm{eV}}{\mathrm{m}}$                   

(2) $\sqrt{\frac{2\mathrm{eV}}{\mathrm{m}}}$

(3) $\sqrt{\frac{2\mathrm{m}}{\mathrm{eV}}}$                 

(4) $\frac{{\mathrm{V}}^2}{2\mathrm{em}}$

Which of the following have the highest specific charge

(1) Positron                   

(2) Proton

(3) ${\mathrm{He}}^{++}$                          

(4) None of these

The idea of matter waves was given by
(1) Davisson and Germer                 

(2) de-Broglie

(3) Einstein                                     

(4) Planck

Waves are associated with matter only: