Physics Crash Course MHT-CET>Chapter 22 - Electrons and Photons>Exercise 1>Q 117

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If the frequency of the incident light falling on a photosensitive material is doubled, then the $K . E$ . of the emitted photoelectron

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Important Questions on Electrons and Photons

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Physics Crash Course MHT-CET>Chapter 22 - Electrons and Photons>Exercise 1>Q 118

The anode voltage of a photocell is kept fixed. The wavelength $\lambda$ 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 Crash Course MHT-CET>Chapter 22 - Electrons and Photons>Exercise 1>Q 120

Einstein's photoelectric equation states that

E_{k} = h v - ϕ .

In this equation

E_{k}

refers to

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Physics Crash Course MHT-CET>Chapter 22 - Electrons and Photons>Exercise 1>Q 121

According to Einstein's photoelectric equation, the graph between the kinetic energy of photoelectrons ejected and the frequency of incident radiation is

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Physics Crash Course MHT-CET>Chapter 22 - Electrons and Photons>Exercise 1>Q 122

Light of wavelength

λ

which is less than threshold wavelength is incident on a photosensitive material. If incident wavelength is decreased then stopping potential will

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Physics Crash Course MHT-CET>Chapter 22 - Electrons and Photons>Exercise 1>Q 123

In a photocell, frequency of incident radiation is increased by keeping other factors constant

(v > v_{0}),

the stopping potential

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Physics Crash Course MHT-CET>Chapter 22 - Electrons and Photons>Exercise 1>Q 124

Following graphs shows the variation of stopping potential corresponding to the frequency of incident radiation (

F

) for a given metal. The correct variation is shown in the graph

(v_{0} = Threshold frequency)

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Physics Crash Course MHT-CET>Chapter 22 - Electrons and Photons>Exercise 1>Q 125

The work function of a metal is

4.2 eV

. Its threshold wavelength will be

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Physics Crash Course MHT-CET>Chapter 22 - Electrons and Photons>Exercise 1>Q 126

Ultraviolet radiations of

6.2 eV

falls on an aluminium surface (work function

4.2 eV

). The kinetic energy in joules of the fastest electron emitted is approximately