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Describe the applications of photoelectric effect.

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6.4 \times 10^{- 19}

joule is approximately

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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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What is photoelectric effect?

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The radiation corresponding to

3 \to 2

transition of a hydrogen atom falls on a gold surface to generate photoelectrons. These electrons are passed through a magnetic field of

5 \times 10^{- 4} T

. Assume that the radius of the largest circular path followed by these electrons is

7 mm

, the work function of the metal is:
(Mass of electron

= 9.1 \times 10^{- 31} kg

)

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When photon of energy

4.0 e V

strikes the surface of a metal

A,

the ejected photoelectrons have maximum kinetic energy

T_{A} e V

and de-Broglie wavelength

λ_{A} .

The maximum kinetic energy of photoelectrons liberated from another metal

B

by photon of energy

4.50 e V

T_{B} = (T_{A} - 1.5) e V .

If the de-Broglie wavelength of these photoelectrons

λ_{B} = 2 λ_{A},

then the work function of metal

B

is:

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What is work function?

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A beam of photons with an energy of

10.5 eV

strike a metal plate. The photoelectrons are emitted with maximum velocity of

1.6 \times 10^{6} m s^{- 1}

. The work function of the metal is
(Assume mass of electron

= 9 \times 10^{- 31} kg

and Charge of electron

= 1.6 \times 10^{- 19} C

)

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If the light of wavelength $412.5 nm$ is incident on each of the metals given below, which ones will show photoelectric emission and why?

Metal	Work Function(eV)
Na	1.92 eV
K	2.15 eV
Ca	3.20 eV
Mo	4.17 eV

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Radiation, with wavelength

6561 Å

falls on a metal surface to produce photoelectrons. The electrons are made to enter a uniform magnetic field of

3 \times 10^{- 4} T

. If the radius of the largest circular path followed by the electrons is

10 m m

, the work function of the metal is close to:

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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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Which of these statements is true regarding photoelectric emission?

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The continuous part of

X

-ray spectrum is a result of the

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The work function of a metal is $1.5 eV .$ Light of wavelength $2500 \overset{o}{A}$ is incident on this metal. Maximum velocity of photoelectrons is

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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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The photoelectric effect proves that

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What is the photoelectric effect? Define Photoelectric work function.

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What is photoelectric effect? Define Stopping potential.

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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?

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A metal surface is illuminated by light of two different wavelengths 248 nm and 310 nm. The maximum speeds of the photoelectrons corresponding to these wavelengths are u₁ and u₂, respectively. If the ratio

u_{1} : u_{2} = 2 : 1

and

h c = 1240 eV nm

, the work function of the metal is nearly

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A photoelectric surface is illuminated successively by monochromatic light of wavelength

λ

and

\frac{λ}{2}

. If the maximum kinetic energy of the emitted photoelectrons in the second case is 3 times that in the first case, the work function of the surface of the material is:
(

h

= Planck's constant,

c

= speed of light)

Describe the applications of photoelectric effect.

Important Questions on Energy Flow and Sources of Energy

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