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When a metallic surface is illuminated with radiation of wavelength $λ,$ the stopping potential is $V$ . If the same surface is illuminated with radiation of wavelength $2 λ,$ the stopping potential is $\frac{V}{4} .$ The threshold wavelength for the metallic surface is

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Important Questions on Dual Nature of Radiation and Atomic Physics

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Physics>Modern Physics>Dual Nature of Radiation and Atomic Physics>Photoelectric Effect - Particle Nature of Light

In a photoelectric experiment, a parallel beam of monochromatic light with the power of

200 W

is incident on a perfectly absorbing cathode of work function

6.25 eV

. The frequency of light is just above the threshold frequency so that the photoelectrons are emitted with negligible kinetic energy. Assume that the photoelectron emission efficiency is 100%. A potential difference of

500 V

is applied between the cathode and the anode. All the emitted electrons are incident normally on the anode and are absorbed. The anode experiences a force

F = n \times 10^{- 4} N

due to the impact of the electrons. The value of

n

is __________. Mass of the electron

m_{e} = 9 \times 10^{- 31} kg a n d 1.0 eV = 1.6 \times 10^{- 19} J

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Physics>Modern Physics>Dual Nature of Radiation and Atomic Physics>Photoelectric Effect - Particle Nature of Light

Light of frequency

1.5

times the threshold frequency is incident on a photosensitive material. What will be the photoelectric current if the frequency is halved and intensity is doubled?

EASY

Physics>Modern Physics>Dual Nature of Radiation and Atomic Physics>Photoelectric Effect - Particle Nature of Light

The photoelectric threshold for a certain metal surface is $360 Å$ . If the metal surface is irradiated by a wavelength of $1100 Å$ , the kinetic energy of the emitted photoelectrons is

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Physics>Modern Physics>Dual Nature of Radiation and Atomic Physics>Photoelectric Effect - Particle Nature of Light

6.4 \times 10^{- 19}

joule is approximately

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Physics>Modern Physics>Dual Nature of Radiation and Atomic Physics>Photoelectric Effect - Particle Nature of Light

The continuous part of

X

-ray spectrum is a result of the

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Physics>Modern Physics>Dual Nature of Radiation and Atomic Physics>Photoelectric Effect - Particle Nature of Light

When a beam of

10.6 eV

photons of intensity

2.0 W m^{- 2}

falls on a metallic surface of area

1 \times 10^{- 4} m^{2}, 0.53 %

of the incident photons eject photoelectrons. What is the number of photoelectrons emitted per second?

EASY

Physics>Modern Physics>Dual Nature of Radiation and Atomic Physics>Photoelectric Effect - Particle Nature of Light

The surface of a metal is illuminated with a light of wavelength

400 nm

. The kinetic energy of the ejected photoelectrons was found to be

1.68 eV

. The work function of the metal is

(h c = 1240 eV nm)

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Physics>Modern Physics>Dual Nature of Radiation and Atomic Physics>Photoelectric Effect - Particle Nature of Light

The work function of copper is

4.7 eV

. If ultraviolet light of wavelength

312 nm

and intensity

1.0 W m^{- 2}

is directed on a copper plate, then in the detector

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Physics>Modern Physics>Dual Nature of Radiation and Atomic Physics>Photoelectric Effect - Particle Nature of Light

Einstein was awarded the Nobel Prize for his work on

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Physics>Modern Physics>Dual Nature of Radiation and Atomic Physics>Photoelectric Effect - Particle Nature of Light

When radiation of wavelength

A

is used to illuminate a metallic surface, the stopping potential is

V

. When the same surface is illuminated with radiation of wavelength

3 A

, the stopping potential is

\frac{V}{4}

. If the threshold wavelength for the metallic surface is

nλ

then value of

n

will be :

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Physics>Modern Physics>Dual Nature of Radiation and Atomic Physics>Photoelectric Effect - Particle Nature of Light

A zinc ball of radius,

R = 1 cm

charged to a potential

- 0.5 V .

The ball is illuminated by a monochromatic ultraviolet

(U V)

light with a wavelength

290 nm .

The photoelectric threshold for zinc is

332 nm .

The potential of ball after a prolonged exposure to the

U V

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Physics>Modern Physics>Dual Nature of Radiation and Atomic Physics>Photoelectric Effect - Particle Nature of Light

The anode voltage of a photocell is kept fixed. The wavelength

λ

of the light falling on the cathode is gradually changed. The plate current

I

of the photocell varies as follows :

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Physics>Modern Physics>Dual Nature of Radiation and Atomic Physics>Photoelectric Effect - Particle Nature of Light

The stopping potential for electrons emitted from a photosensitive surface illuminated by light of wavelength

491 nm

0.710 V .

When the incident wavelength is changed to a new value, the stopping potential is

1.43 V .

The new wavelength is :

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Physics>Modern Physics>Dual Nature of Radiation and Atomic Physics>Photoelectric Effect - Particle Nature of Light

The following graph represents the variation of photo current with anode potential for a metal surface. Here $I_{1}, I_{2}$ and $I_{3}$ represents intensities and $γ_{1}, γ_{2}, γ_{3}$ represents frequency for curves $1, 2$ and $3$ respectively, then

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Physics>Modern Physics>Dual Nature of Radiation and Atomic Physics>Photoelectric Effect - Particle Nature of Light

The stopping potential in the context of photoelectric effect depends on the following property of incident electromagnetic radiation:

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Physics>Modern Physics>Dual Nature of Radiation and Atomic Physics>Photoelectric Effect - Particle Nature of Light

The minimum negative potential given to anode plate at which photoelectric current becomes zero is called

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Physics>Modern Physics>Dual Nature of Radiation and Atomic Physics>Photoelectric Effect - Particle Nature of Light

The work function of three photosensitive materials used to build photoelectric devices are given as : Sodium $(2.75 eV),$ copper $(4.65 eV)$ and gold $(5.1 eV) .$ Which of the following statements is correct. (The frequency of visible light lies in the range $4 \times 10^{14} Hz$ to $8 \times 10^{14} Hz) ?$

MEDIUM

Physics>Modern Physics>Dual Nature of Radiation and Atomic Physics>Photoelectric Effect - Particle Nature of Light

Given figure shows few data points in a photo-electric effect experiment for a certain metal. The minimum energy for ejection of electrons from its surface is: (Planck's constant $h = 6.62 \times 10^{- 34} J.s$ )

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Physics>Modern Physics>Dual Nature of Radiation and Atomic Physics>Photoelectric Effect - Particle Nature of Light

The radiation corresponding to

3 \to 2

transition of hydrogen atom falls on a metal surface to produce photoelectrons. These electrons are made to enter a magnetic field of

3 \times 1 0^{- 4} T

. If the radius of the largest circular path followed by these electrons is 10.0 mm, the work function of the metal is close to :

EASY

Physics>Modern Physics>Dual Nature of Radiation and Atomic Physics>Photoelectric Effect - Particle Nature of Light

When a certain photosensitive surface is illuminated with a monochromatic light of frequency

ν,

the stopping potential of the photo current is

- \frac{V_{0}}{2} .

When the surface is illuminated by monochromatic light of frequency

\frac{ν}{2},

the stopping potential is

- V_{0} .

The threshold frequency for photoelectric emission is

When a metallic surface is illuminated with radiation of wavelength λ, the stopping potential is V. If the same surface is illuminated with radiation of wavelength 2λ, the stopping potential is V4. The threshold wavelength for the metallic surface is

Important Questions on Dual Nature of Radiation and Atomic Physics

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When a metallic surface is illuminated with radiation of wavelength $λ,$ the stopping potential is $V$ . If the same surface is illuminated with radiation of wavelength $2 λ,$ the stopping potential is $\frac{V}{4} .$ The threshold wavelength for the metallic surface is