Dual nature of radiation and matter practice · Medium

A 5 W source emits monochromatic light of wavelength $5000\mathop A\limits^ \circ$. When placed 0.5 m away, it liberates photoelectrons from a photosensitive metallic surface. When the source is moved to a distance of 1.0m, the number of photoelectrons liberated will be reduced by a factor of

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

The time taken by a photoelectron to come out after the photon strikes is approximately

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

Colour of star is an indication of its:-

Moving with the same velocity. Which of the following has the longest be Broglie wavelength

For a body moving with relativistic speed, if the velocity is doubled, then

If the frequency of light in a photoelectric
experiment is doubled, the stopping potential will:

The debroglie wavelength of an electron is $\lambda$ and has energy ${E}$. If the de Broglie wavelength is reduced by $25 \%$, then how much extra kinetic energy will the electron have now

The special theory of relativity is based on the frame of reference which has constant?

Ultraviolet radiation of 6.2eV falls on an aluminium surface (work function 4.2eV). The kinetic energy in joule of the fastest electron emitted is approximately

The colour of the positive column in a gas discharge tube depends on

Doubly ionised helium atom and hydrogen ions are accelerated, from rest, through the same potential difference. The ratio of final velocities of helium and hydrogen is

The de-Broglie wavelength is proportional to

In the photoeletric effect, electrons are emitted

Planck’s constant has the dimensions of

If ${\mathrm{g}_E}$ and ${\mathrm{g}_M}$ are the acceleration due to gravity on the surfaces of the earth and the moon respectively and it Millikan’s oil drop experiment could be performed on the two surfaces, one will find the ratio $\frac{{\mathrm{electronic\;charge\;on\;the\;moon\;}}}{{\mathrm{electronic\;charge\;on\;the\;earth\;}}}$ to be

An electron is accelerated under a potential difference of 182 V. The maximum velocity of electron will be
(Charge of an electron is $1.6 \times {10^{ - 19}}$ C and its mass is $9.1 \times {10^{ - 31}}\;$ kg)

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

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