If the work function of a metal is $6.622 \times {10}^{-20} J$ and a ray of electromagnetic radiation with a frequency of $1.0 \times {10}^{14} Hz$ is incident on the metal, what will be the speed of the electrons ejected from the metal?$( Note:h = 6.626 \times {10}^{-34} J-s \mathrm{and} m_e -=9.1 \times {10}^{-31} kg)$

1.  $2.62 \times {10}^{-6} \frac{m}{s}$

2.  $1.07 \times {10}^{-4} \frac{m}{s}$

3.  $9.38 \times {10}^3 \frac{m}{s}$

4.  $3.81 \times {10}^5 \frac{m}{s}$

All of the following statements about the photoelectric effect are true Except:

1. the intensity Of the light beam does not affect the photocurrent.

2. the kinetic energies of the emitted electrons do not depend on the light intensity.

3. a weak beam Of light Of frequency greater than the threshold frequency yields more current than an intense beam of light of frequency lower than the threshold frequency.

4. for the light of a given frequency, the kinetic energy of emitted electrons increases as the value of the work function decreases.

Let $n_r and n_b$ be respectively the number of photons emitted by a red bulb and a blue bulb of equal power in a given time.

1. $n_r=n_b$

2. $n_r<n_b$

3. $n_r>n_b$

4. data insufficient

When a photon of light collides with a metal surface, the number of electrons, (if any) coming out is:

1. only one

2. only two

3. infinite

4. depends upon factors

A point source of light is used in the photoelectric effect. If the source is removed farther from the emitting metal, the stopping potential:

1. will increase

2. will decrease

3. will remain constant

4. will either increase or decrease

What is the de-Broglie wavelength of a nitrogen molecule in air at 300 K? Assume that the molecule is moving with the root-mean-square speed of molecules at this temperature. ( Atomic mass of nitrogen = 14.0076 u)

1 0.01 nm

2 0.09 nm 

3 0.03 nm 

4 0.2 nm

In a photoelectric experiment, electrons are ejected from metals X and Y by the light of intensity I and frequency f. The potential difference V required to stop the electrons is measured for various frequencies. If Y has a greater work function than X; which one of the following graphs best illustrates the expected results?

1. 

2. 

3. 

4.

An electron with the initial kinetic energy of 100 eV is accelerated through a potential difference of 50 V. Now the de-Broglie wavelength of electron becomes-

1. 1 $\stackrel{0}{A}$

2. $\sqrt{1.5}$ $\stackrel{0}{A}$

3. $\sqrt{3}$$\stackrel{0}{A}$

4. 12.27 $\stackrel{0}{A}$

The de-Broglie wavelength L associated with an elementary particle of linear momentum p is best represented by the graph:

1. 

2. 

3. 

4. 

An electron of mass m, when accelerated through a potential difference, has de-Broglie wavelength $\lambda$ .The de-Broglie wavelength associated with a proton of mass M accelerated through the same potential difference will be:

1. $\lambda \frac{m}{M}$

2. $\lambda \sqrt{\frac{m}{M}}$

3. $\lambda \frac{M}{m}$

4. $\lambda \sqrt{\frac{M}{m}}$