Dual nature of radiation and matter practice · Mixed difficulty

Intensity of U.V. radiations is $10 \mathrm{~Watt} / \mathrm{m}^2$ and its average wavelength is
$6000 \mathop {\text{A}}\limits^{\text{o}}$. It is incident on a surface. Calculate number of photons per 2 sec. per $2 \mathrm{~m}^2$.

Cut off potentials for a metal surface for light of wavelengths $\lambda_1, \lambda_2$ and $\lambda_3$ are $V_1, V_2$ and $V_3$ respectively. If $V_1, V_2$ and $V_3$ are in arithmatic progression, then $\lambda_1, \lambda_2$ and $\lambda_3$ are in

Statement-1: Photoelectric effect establishes quantum nature of light.
Statement-2: There is negligible time lag between photon collisions with the material and photoelectron emission irrespective of intensity of incident light. (Assume incident light is of frequency greater than threshold frequency of the material).

If wavelength of photon and electron is same then ratio of total energy of electron to total energy of photon would be

Radius of central zone of circular zone plate is 2.3 mm. wavelength of incident light is 5893 ${A^ \circ }$. Source is at a distance of 6 m. Then the distance of first image will be

A proton and an electron have the same de Broglie wavelength. If $\mathrm{K}_{\mathrm{p}}$ and $\mathrm{K}_{\mathrm{e}}$ be the kinetic energies of proton and electron respectively. Then choose the correct relation:

Assertion: Photoelectric effect is seen only when electron are bound.

Reason: Free electron cannot absorb whole energy of photon and consuming momentum and energy.

What will be the ratio of the de-Broglie wavelength of proton and $\alpha$ particle of same energy?

When the speed of electrons increase, then the value of its specific charge

An $\alpha$-particle and a proton are accelerated from rest by a potential difference of 100 V. After this, their de-Broglie wavelengths are ${\lambda _\alpha }$ and ${\lambda _p}$ respectively. The ratio $\frac{{{\lambda _p}}}{{{\lambda _\alpha }}}$, to the nearest integer, is

Consider the two following statements I and II, and identify the correct choice given in the answers

III. In photovoltaic cells the photoelectric current produced is not proportional to the intensity of incident light.

IV. In gas filled photoemissive cells, the velocity of photoelectrons depends on the wavelength of the incident radiation.

G. P. Thomson experimentally confirmed the existence of matter waves by the phenomenon

Experimental study of photoelectric effect shows that

I. Photocurrent $\propto$ intensity of light.

II. saturation current $\propto$ intensity of light.

III. photoemission occurs only at frequency greater than threshold frequency.

IV. photoemission is an instantaneous process.

The correct statements are

When radiation of wavelength $\lambda$ is incident on a metallic surface, the stopping potential of ejected photoelectrons is 4.8 V. If the same surface is illuminated by radiation of double the previous wavelength, then the stopping potential becomes 1.6 V. The threshold wavelength of the metal is

In Millikan’s oil drop experiment, a charged drop of mass $1.8 \times {10^{ - 14}}$ kg is stationary between the plates. The distance between the plates 0.9 cm and potential difference between the plates is 2000 V. The number of electrons on the oil drop is

Statement 1: The photoelectric effect is proof of the quantised nature of light.

Statement 2: Each photon in light beam has same amount of energy

If a proton and electron have the same de Broglie wavelength, then

Cathode rays are

Threshold wavelength for photoelectric effect on sodium is $5000\;\mathop A\limits^ \circ .$ Its work function is

The de Broglie wavelength of an electron having kinetic energy $E$ is $\lambda$. If the kinetic energy of electron becomes $\frac{E}{4}$, then its de-Broglie wavelength will be:

If the work function of a metal is $6.63 \mathrm{~eV}$, then find its threshold frequency for photoelectric effect.

$\alpha -$ particle contain –

The number of photons per second on an average emitted by the source of monochromatic light of wave length 1200 nm, when it delivers the power $3.3 \times {10^{ - 3}}\,\,{\text{watt}}$ will be $\left[ {h = 6.6 \times {{10}^{ - 34}}\,\,J\,\,s} \right]$

Find the de-Broglie wavelength associated with an electron moving with a velocity $0.5c$ and rest mass $=9.1 \times 10^{-31} \mathrm{~kg}$.

The mean free path of the electrons in a discharge tube is 20 cm. The length of the tube is 15 cm only. Then length of Crooke’s dark space is

If wavelength of radiation is $4000 \mathop {\text{A}}\limits^{\text{o}}$, then the energy of the photon is.

In photo electric effect

A. The photocurrent is proportional to the intensity
of the incident radiation.

B. Maximum kinetic energy with which
photoelectrons are emitted depends on the
intensity of incident light.

C. Max. K.E with which photoelectrons are emitted
depends on the frequency of incident light.

D. The emission of photoelectrons require a
minimum threshold intensity of incident
radiation.

E. Max. K.E of the photoelectrons is independent
of the frequency of the incident light.

Choose the correct answer from the options given
below:

Assertion: In photo-particle collision the total energy and total momentum are conserved.

Reason: the number of photos are conserved in a collision.

Assertion: The kinetic energy of photoelectrons emitted from metal surface does not depend on the intensity of incident photon.

Reason: The ejection of electrons from metallic surface is not possible with frequency of incident photons below the threshold frequency.

Assertion (A): Work function of aluminium is 4.2 eV. Emission of electron will not be possible if two photons each of energy 2.5 eV strike an electron of a aluminium.
Reason (R): For photoelectron emission the energy of each photon should be greater than the work function of metal.