Back to DUAL NATURE OF RADIATION AND MATTER

JEE PHYSICS MCQ: DUAL NATURE OF RADIATION AND MATTER

1 Medium

1 of 1

Application +4 | -1

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

.

View answer and explanation

Correct option: A

1.2 \times 10^{20}

Option A (

1.2 \times 10^{20}

) is correct because it is the number of photons calculated using the given intensity, wavelength, and area over a time of 2 seconds.

More Questions from DUAL NATURE OF RADIATION AND MATTER

Practice All Chapter MCQs →

The electrons are emitted in the photoelectric effect from a metal surface What is the de Broglie wavelength of a bullet of mass 0.04 kg travelling at the speed of 1 km/s? Photoelectrons are emitted from a metal surface when UV light of wavelength

\lambda=300 \mathrm{~nm}

is incident on it. The minimum negative potential required to stop the emission of electrons is

0.54 \mathrm{~V}

. Calculate:
(i) the energy of the incident photons
(ii) the maximum kinetic energy of the photoelectrons emitted. An electron is accelerated by a potential difference of V volt to acquire kinetic energy equal to maximum kinetic energy of ejected photoelectron from a metal of work function 3.2 eV, using a light of wavelength

2000\,\mathop \mathrm{A}\limits^ \circ \,

Value of V is Two monochromatic beams

A

B

of equal intensity

I

, hit a screen. The number of photons hitting the screen by beam

A

is twice that by beam

B

. Then, what can inference you about their frequencies? 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