A point source of light is used in an experiment of photoelectric effects. If the distance between the source and the photoelectric surface is doubled, which of the following may result?

Photoelectric current will decrease.

Stopping potential will be halved.

Maximum kinetic energy of photoelectrons will decrease.

Stopping potential will increase slightly.

Electrons are emitted with kinetic energy T from a metal plate by an irradiation of light of intensity J and frequency v . Then, which of the following will be true?

Number of electrons emitted ∝ J

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When the light of frequency $v_{1}$ is incident on metal with work function $W_{0}$ (where $h v_{1} > W_{0}),$ the photocurrent falls to zero at a stopping potential of $V_{1} .$ If the frequency of light is increased to $v_{2}$ , the stopping potential changes to $V_{2}$ . Therefore, the charge of an electron is given by

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Important Questions on Dual Nature of Matter and Radiation

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Physics Crash Course JEE Advanced>Chapter 19 - Dual Nature of Matter and Radiation>Exercise 1>Q 11

The maximum wavelength of radiation that can produce photoelectric effect in a certain metal is

200 nm

. The maximum kinetic energy acquired by electron due to radiation of wavelength

100 nm

will be

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Physics Crash Course JEE Advanced>Chapter 19 - Dual Nature of Matter and Radiation>Exercise 1>Q 12

A metal surface of work function

1.07 eV

is irradiated with light of wavelength

332 nm

. The retarding potential required to stop the escape of photo-electrons is

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Physics Crash Course JEE Advanced>Chapter 19 - Dual Nature of Matter and Radiation>Exercise 1>Q 13

The velocity of the most energetic electrons emitted from a metallic surface is doubled when the frequency

v

of the incident radiation is doubled. The work function of the metal is

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Physics Crash Course JEE Advanced>Chapter 19 - Dual Nature of Matter and Radiation>Exercise 1>Q 14

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

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Physics Crash Course JEE Advanced>Chapter 19 - Dual Nature of Matter and Radiation>Exercise 1>Q 15

Light of wavelength $2475 \overset{\circ}{A}$ is incident on barium. Photoelectrons emitted describe a circle of the radius $100 cm$ by a magnetic field of flux density $\frac{1}{\sqrt{17}} \times 10^{- 5} T$ . The work function of the barium is: (Given $\frac{e}{m} = 1.7 \times 10^{11} C {kg}^{- 1}$ .)

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Physics Crash Course JEE Advanced>Chapter 19 - Dual Nature of Matter and Radiation>Exercise 1>Q 16

In Davisson-Germer experiment, an electron beam of energy

60 eV

falls normally on the surface of a crystal. If the maximum intensity is obtained at an angle of

60^{\circ}

to the direction of incident beam, then the inter-atomic distance in the lattice plane of the crystal will be:

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Physics Crash Course JEE Advanced>Chapter 19 - Dual Nature of Matter and Radiation>Exercise 1>Q 17

When photons of energy

4.0 eV

fall on the surface of a metal

A

, the ejected photoelectrons have maximum kinetic energy

T_{A}

(in

eV

) and a de-Broglie wavelength

λ_{A}

. When the same photons fall on the surface of another metal

B

, the maximum kinetic energy of ejected photoelectrons is

T_{B} = T_{A} - 1 .5 eV

. If the de-Broglie wavelength of these photoelectrons is

λ_{B} = 2 λ_{A}

, then the work function of metal

B

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Physics Crash Course JEE Advanced>Chapter 19 - Dual Nature of Matter and Radiation>Exercise 1>Q 18

An electron in metal at

27 ° C

has a de-Broglie wavelength of ...

(Given m_{e} = 9 .1 \times 10^{- 31} kg, k_{B} = 1 .38 \times 10^{- 23} J K^{- 1})

When the light of frequency $v_{1}$ is incident on metal with work functionW0 (wherehv1>W0, the photocurrent falls to zero at a stopping potential of V1. If the frequency of light is increased to v2, the stopping potential changes toV2 . Therefore, the charge of an electron is given by

Important Questions on Dual Nature of Matter and Radiation

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