What will be the momentum, of the electrons accelerated through a potential difference of 56 V.
$$\begin{gathered} \left(1\right) 4.07\times {10}^{-25 }\mathrm{kg} {\mathrm{ms}}^{-1} \\ \left(2\right) 4.04\times {10}^{-24 }\mathrm{kg} {\mathrm{ms}}^{-1} \\ \left(3\right) 4.07\times {10}^{-24 }\mathrm{kg} {\mathrm{ms}}^{-1} \\ \left(4\right) 4.04\times {10}^{-25 }\mathrm{kg} {\mathrm{ms}}^{-1} \end{gathered}$$

What is the de Broglie wavelength of an electron with the kinetic energy of 120 eV?
 

For what kinetic energy of a neutron will the associated de Broglie wavelength be
1.40 x ${10}^{-10}$ m?

$$\begin{gathered} \left(1\right) 1.1\times {10}^{-2} eV \\ \left(2\right) 2.1\times {10}^{-2} eV \\ \left(3\right) 3.3\times {10}^{-2} eV \\ \left(4\right) 4.2\times {10}^{-2} eV \end{gathered}$$

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)

 About 5% of the power of a 100 W light bulb is converted to visible radiation. What is the average intensity of visible radiation at a distance of 1 m from the bulb?

$$\begin{gathered} \left(1\right) 0.472 W/m^2 \\ \left(2\right) 0.398 W/m^2 \\ \left(3\right) 0.323 W/m^2 \\ \left(4\right) 0.401 W/m^2 \end{gathered}$$

What is the de Broglie wavelength of a bullet of mass 0.040 kg traveling at the speed of 1.0 km/s?

$$\begin{gathered} \left(1\right) 1.65\times {10}^{-35} \mathrm{m} \\ \left(2\right) 1.05\times {10}^{-35} \mathrm{m} \\ \left(3\right) 2.15\times {10}^{-35} \mathrm{m} \\ \left(4\right) 2.11\times {10}^{-35} \mathrm{m} \end{gathered}$$ 

 An electron and a photon each have a wavelength of 1.00 nm. The momentum of the electron will be:

The work function of cesium metal is 2.14 eV. When light of frequency 6 × 10¹⁴ Hz is incident on the metal surface, photoemission of electrons occurs. What is the stopping potential of the metal?

The photoelectric cut-off voltage in a certain experiment is 1.5 V. What is the maximum kinetic energy of photoelectrons emitted?

$$\begin{gathered} \left(1\right) 2.1\times {10}^{-19} J \\ \left(2\right) 1.7\times {10}^{-19} J \\ \left(3\right) 2.4\times {10}^{-19} J \\ \left(4\right) 1.1\times {10}^{-19} J \end{gathered}$$

Monochromatic light of wavelength 632.8 nm is produced by a
helium-neon laser. The power emitted is 9.42 mW. The energy of each photon in the light beam is:

$$\begin{gathered} \left(1\right) 4.801\times {10}^{-19} J \\ \left(2\right) 2.121\times {10}^{-19} J \\ \left(3\right) 5.043\times {10}^{-19} J \\ \left(4\right) 3.141\times {10}^{-19} J \end{gathered}$$

The energy flux of sunlight reaching the surface of the earth is 1.388 × 10³ W/m². How many photons(nearly) per square meter are incident on the Earth per second? Assume an average wavelength of 550 nm.

In an experiment on the photoelectric effect, the slope of the cut-off voltage versus frequency of incident light is found to be $4.12\times {10}^{-15} V s$. The value of Planck's constant is:

A 100 W sodium lamp radiates energy uniformly in all directions. The lamp is located at the center of a large sphere that absorbs all the sodium light which is incident on it. The wavelength of sodium light is 589 nm. What is the energy per photon associated with the sodium light?

$$\begin{gathered} \left(1\right) 1.21 eV \\ \left(2\right) 2.21 eV \\ \left(3\right) 2.11 eV \\ \left(4\right) 1.11 eV \end{gathered}$$

Light of frequency $7.21\times {10}^{14} \mathrm{Hz}$ is incident on a metal surface. Electrons with a maximum speed of $6.0\times {10}^5 \mathrm{m}/\mathrm{s}$ are ejected from the surface. What is the threshold frequency for the photoemission of electrons?

$$\begin{gathered} \left(1\right) 5.109\times {10}^{14} Hz \\ \left(2\right) 3.345\times {10}^{14} Hz \\ \left(3\right) 6.733\times {10}^{14} Hz \\ \left(4\right) 4.738\times {10}^{14} Hz \end{gathered}$$

The threshold frequency for a certain metal is $3.3\times {10}^{14} \mathrm{Hz}.$ If the light of frequency $8.2\times {10}^{14} \mathrm{Hz}$ is incident on the metal, the cut-off voltage for the photoelectric emission is:

Light of intensity 10^-5 W m^-2 falls on a sodium photo-cell of surface area 2 cm². Assuming that the top 5 layers of sodium absorb the incident energy, The time required for photoelectric emission in the wave-picture of radiation is: (The work function for the metal is given to be about 2 eV.)

Monochromatic radiation of wavelength 640.2 nm (1 nm = 10^-9 m) from a neon lamp irradiates photosensitive material made of cesium on tungsten. The stopping voltage is measured to be 0.54 V. The source is replaced by an iron source and its 427.2 nm line irradiates the same photo-cell. The new stopping voltage is:

Ultraviolet light of wavelength 2271 Å from a 100 W mercury source irradiates a photocell made of molybdenum metal. If the stopping potential is −1.3 V, the work function of the metal is:

The work function of caesium is 2.14 eV. The threshold frequency for caesium is:

$$\begin{gathered} 1. 5.03\times {10}^{12} \mathrm{Hz} \\ 2. 6.12\times {10}^{14} \mathrm{Hz} \\ 3. 5.16\times {10}^{14} \mathrm{Hz} \\ 4. 6.51\times {10}^{12} \mathrm{Hz} \end{gathered}$$

In an accelerator experiment on high-energy collisions of electrons with positrons, a certain event is interpreted as the annihilation of an electron-positron pair of total energy 10.2 BeV into two γ-rays of equal energy. What is the wavelength associated with each γ-ray? (1BeV = 109 eV)

$$\begin{gathered} \left(1\right) 3.4\times {10}^{-16} m \\ \left(2\right) 1.7\times {10}^{-16} m \\ \left(3\right) 2.4\times {10}^{-16} m \\ \left(4\right) 3.1\times {10}^{-16} m \end{gathered}$$

The typical de Broglie wavelength of an electron in metal at $27 °C$ will be:

$$\begin{gathered} \left(1\right) 4.4\times {10}^{-10} m \\ \left(2\right) 3.4\times {10}^{-9} m \\ \left(3\right) 1.3\times {10}^{-10} m \\ \left(4\right) 6.2\times {10}^{-9} m \end{gathered}$$

The typical de Broglie wavelength associated with a He atom in helium gas at room temperature $\left(27 °C\right)$ and 1 atm pressure will be:

$$\begin{gathered} \left(1\right) 4.63\times {10}^{-11} m \\ \left(2\right) 6.2\times {10}^{-12} m \\ \left(3\right) 7.3\times {10}^{-11} m \\ \left(4\right) 5.7\times {10}^{-12} m \end{gathered}$$

An electron microscope uses electrons accelerated by a voltage of 50 kV. The de Broglie wavelength associated with the electrons is:

$$\begin{gathered} \left(1\right) 6.7\times {10}^{-12} m \\ \left(2\right) 5.4\times {10}^{-12} m \\ \left(3\right) 8.5\times {10}^{-12} m \\ \left(4\right) 4.4\times {10}^{-12} m \end{gathered}$$

The de-Broglie wavelength of an electron moving with the kinetic energy of 144 eV is nearly equal to:

The wave nature of electrons was experimentally verified by, 

A particle is dropped from a height H. The de-Broglie wavelength of the particle as a function of height is proportional to:

The wavelength of a photon needed to remove a proton from a nucleus which is bound to the nucleus with 1 MeV energy is nearly

Consider a beam of electrons (each electron with energy E₀) incident on a metal surface kept in an evacuated chamber. Then,

Consider figure given below. Suppose the voltage applied to A is increased. The diffracted beam will have the maximum at a value of $\mathrm{\theta }$ that
                  

A particle moves in a closed orbit around the origin, due to a force which is directed towards the origin. The de-Broglie wavelength of the particle varies cyclically between two values ${\mathrm{\lambda }}_1, {\mathrm{\lambda }}_2$ with ${\mathrm{\lambda }}_1>{\mathrm{\lambda }}_2$. Which of the following statement/s is/are true?

(a) The particle could be moving in a circular orbit with origin as the centre.
(b) The particle could be moving in an elliptic orbit with origin as its focus.
(c) When the de-Broglie wavelength is ${\mathrm{\lambda }}_1$, the particle is nearer the origin than when its value is ${\mathrm{\lambda }}_2$.
(d) When the de-Broglie wavelength is ${\mathrm{\lambda }}_2$, the particle is nearer the origin than when its value is ${\mathrm{\lambda }}_1$.