$\mathrm{A} 200\mathrm{W} \mathrm{sodium} \mathrm{street} \mathrm{lamp} \mathrm{emits} \mathrm{yellow} \mathrm{light} \mathrm{of} \mathrm{wavelength} 0.60\mathrm{\mu m}. \mathrm{Assuming} \mathrm{it} \mathrm{to} \mathrm{be}$
$50\% \mathrm{efficient}, \mathrm{in} \mathrm{converting} \mathrm{electrical} \mathrm{energy} \mathrm{into} \mathrm{light}, \mathrm{the} \mathrm{number} \mathrm{of} \mathrm{photons} \mathrm{of} \mathrm{yellow}$
$\mathrm{light} \mathrm{emitted} \mathrm{per} \mathrm{second} \mathrm{is} \mathrm{nearly} \mathrm{equal} \mathrm{to}-$

1.  $3 x {10}^{19}$

2.  $3 x {10}^{20}$

3.  $1.5 x {10}^{20}$

4.  $6 x {10}^{20}$

A radiation of energy 'E' falls normally on a perfectly reflecting surface. The momentum transferred to the surface is (c=velocity of light)

1. E/c

2. 2E/c

3. 2E/c²

4. E/c²

Particle nature and wave nature of electromagnetic waves and electrons can be shown by 

(1) Electron has small mass, deflected by the metal sheet

(2) X-ray is diffracted, reflected by thick metal sheet

(3) Light is refracted and defracted

(4) Photoelectricity and electron microscopy

Momentum of a photon of wavelength $\mathrm{\lambda }$ is

(a) $\frac{\mathrm{h}}{\mathrm{\lambda }}$            (b) Zero
(c) $\frac{\mathrm{h\lambda }}{{\mathrm{c}}^2}$          (d) $\frac{\mathrm{h\lambda }}{\mathrm{c}}$

The photoelectric threshold wavelength for a metal surface is 6600 Å. The work function for this is 
(1) 1.87 V                             

(2) 1.87 eV

(3) 18.7 eV                             

(4) 0.18 eV

The maximum kinetic energy of photoelectrons emitted from a surface when photons of energy 6 eV fall on it is 4 eV. The stopping potential in volts is

(1) 2                     

(2) 4

(3) 6                     

(4) 10

A beam of light of wavelength \(\lambda\) and with illumination \(L\) falls on a clean surface of sodium. If \(N\) photoelectrons are emitted each with kinetic energy \(E\), then:
1. \(N \propto L \) and \(E \propto L \)
2.  \(N \propto L \) and \(E \propto \frac{1}{\lambda}\)
3.  \(N \propto \lambda\) and \(E \propto L \)
4.  \(N \propto \frac{1}{\lambda}\) and \(E \propto \frac{1}{L}\)

Light of frequency v is incident on a substance of threshold frequency ${\mathrm{v}}_0\left({\mathrm{v}}_0<\mathrm{v}\right)$. The energy of the emitted photo-electron will be 
(a) $\mathrm{h}\left(\mathrm{v}-{\mathrm{v}}_0\right)$                  (b) h/v
(c) $\mathrm{he}\left(\mathrm{v}-{\mathrm{v}}_0\right)$                (d) $\mathrm{h}/{\mathrm{v}}_0$

4 eV is the energy of the incident photon and the work function in 2eV. What is the stopping potential ?

(1) 2V                   

(2) 4V

(3) 6V                   

(4) $2\sqrt{2} \mathrm{V}$