﻿ When a metallic surface is illuminated with radiation of wavelength , the stopping potential is V. If the same surface is illuminated with radiation of wavelength 2 , the stopping potential is V/4. The threshold wavelength for the metallic surface is, from Physics Dual Nature of Radiation and Matter Class 12 Himachal Pradesh Board

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When a metallic surface is illuminated with radiation of wavelength , the stopping potential is V. If the same surface is illuminated with radiation of wavelength 2 , the stopping potential is V/4. The threshold wavelength for the metallic surface is,

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When a metallic surface is illuminated with radiation of wavelength , the stopping potential is V.

Photoelectric equation can be written as,

... (i)
Now, when the same surface is illuminated with radiation of wavelength 2, the stopping potential is V/4. So, photoelectric equation can be written as,

From equations (i) and (ii), we get

When a metallic surface is illuminated with radiation of wavelength , the stopping potential is V.

Photoelectric equation can be written as,

... (i)
Now, when the same surface is illuminated with radiation of wavelength 2, the stopping potential is V/4. So, photoelectric equation can be written as,

From equations (i) and (ii), we get

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What is the de-Broglie wavelength of
(a)    a bullet of mass 0.040 kg travelling at the speed of 1.0 km/s.
(b)    a ball of mass 0.060 kg moving at a speed of 1.0 m/s and
(c)    a dust particle of mass 1.0 x 10–9 kg drifting with a speed of 2.2 m/s?

(a) Given,

$\therefore$ De-broglie wavelength is,

(b) Mass of the ball,
Velocity with which the ball is moving,
Momentum of the particle,

Therefore,

De-broglie wavelength of the particle,

(c) Mass of the dust particle,

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

b.) How many photons per second, on the average arrive at a target irradiated by this beam?

c.) How fast does a hydrogen atom have to travel in order to have the same  momentum as that of the photon?

Given,
Wavelength of monochromatic light, λ = 632.8 nm = 632.8 x 10
–9 m
$\therefore$ Frequency,

(a) Energy of a photon,

Momentum of each photon,

(b) Power emitted, P = 9.42 mW = 9.42 x 10–3 W
Now,

This implies,

Thus, these many number of protons arrive at the target.

(c) Velocity of hydrogen atom

Thus, the hydrogen atom travel at a speed of 0.63 m/s  to have the same  momentum as that of the photon.
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The energy flux of sunlight reaching the surface of the earth is 1.388 x 103 W/m2. How many photons (nearly) per square metre are incident on the earth per second? Assume that the photons in the sunlight have an average wavelength of 550 nm.

Energy flux of sunlight = Total energy per square metre per second = 1.388 x 103 Wm–2

Energy of each photon is given by,

Therefore,

Number of photons incident on earth's surface per square metre per second is,

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Calculate the
(a)    momentum, and
(b)    de-Broglie wavelength of the electrons accelerated through a potential difference of 56 V.

Given,
Potential difference, V = 56 V

Energy of electron accelerated,

(a) As, Energy,
$\therefore$

$⇒$

$⇒$

is the momentum of the electron.

(b) Now, using De-broglie formula we have,
$\therefore$

i.e.,     is the De-broglie wavelength of the electron.
484 Views

What is the
(a)    momentum,
(b)    speed, and
(c)    de-Broglie wavelength of an electron with kinetic energy of 120 eV.

given,
Kinetic energy of the electron, K.E = 120 eV

(a) Momentum of the electron is given as,

$⇒$

(b) Now, since
we have,

$⇒$

(c) De- broglie wavelength of electron is given by,

830 Views