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Threshold frequency is :

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Important Questions on Dual Nature of Radiation and Atomic Physics

MEDIUM

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 :

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)

EASY

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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HARD

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

EASY

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

EASY

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

6.4 \times 10^{- 19}

joule is approximately

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

MEDIUM

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 $8 \times 10^{14} Hz) ?$

HARD

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 :

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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MEDIUM

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 :

HARD

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

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

EASY

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?

MEDIUM

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

EASY

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

The number of photoelectrons emitted per unit area and unit time is directly proportional to [given that

V > V_{o}]

EASY

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

MEDIUM

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?

MEDIUM

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

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

In P.E.E. obtain graph is : Threshold frequency is :

Important Questions on Dual Nature of Radiation and Atomic Physics

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In $P . E . E$ . obtain graph is :

Threshold frequency is :