The maximum velocity of an electron emitted by light of wavelength λ incident on the surface of a metal of work function ϕ is 
(a) 2hc+λϕ1/2        (b) 2hc+λϕ1/2
(c) 2hc-λϕ1/2        (d) 2-ϕm1/2

Where h = Planck's constant, m = mass of electron and c = speed of light.

Concept Questions :-

Einstein photo-electric equation
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In a photoemissive cell with executing wavelength λ, the fastest electron has speed v. If the exciting wavelength is changed to 3λ/4, the speed of the fastest emitted electron will be 
(a) v3/41/2                              (b) v4/31/2
(c) Less than v4/31/2               (d) Greater than v4/31/2

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Photoelectric effect experiment
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Photoelectric emission is observed from a metallic surface for frequencies v1 and v2 of the incident light rays v1>v2. If the maximum values of kinetic energy of the photoelectrons emitted in the two cases are in the ratio of 1:k, then the threshold frequency of the metallic surface is

(a) v1-v2k-1           (b) kv1-v2k-1
(c) kv2-v1k-1         (d) v2-v1k

Concept Questions :-

Electron emission
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The ratio of de-Broglie wavelengths of molecules of hydrogen and helium which are at temperature 27 °C and 127 °C respectively is
(a) 12               

(b) 38
(c) 83             

(d) 1

Concept Questions :-

De-broglie wavelength
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A photon of wavelength 6630 Å is incident on a totally reflecting surface. The momentum delivered by the photon is equal to

(a) 6.63×10-27 kg-m/sec                           

(b) 2×10-27 kg-m/sec

(c) 10-27 kg-m/sec                                     

(d) None of these

Concept Questions :-

De-broglie wavelength
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The ratio of de-Broglie wavelength of a α-particle to that of a proton being subjected to the same magnetic field so that the radii of their path are equal to each other assuming the field induction vector B is perpendicular to the velocity vectors of the α-particle and the proton is
(a) 1                     

(b) 14
(c) 12                   

(d) 2

Concept Questions :-

De-broglie wavelength
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In a photocell bichromatic light of wavelength 2475 Å and 6000 Å are incident on cathode whose work function is 4.8 eV. If a uniform magnetic field of 3×10-5 Tesla exists parallel to the plate, the radius of the path described by the photoelectron will be (mass of electron = 9×10-31 kg)

(a) 1 cm                     

(b) 5 cm

(c) 10 cm                     

(d) 25 cm

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Einstein photo-electric equation
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Which of the following figure represents the variation of particle momentum and the associated de-Broglie wavelength

Concept Questions :-

De-broglie wavelength
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The figure shows the variation of photocurrent with anode potential for a photo-sensitive surface for three different radiations. Let Ia,Ib and Ic be the intensities and fa,fb and fc be the frequencies for the curves a, b and c respectively 

(a) fa=fb  and IaIb 
(b) fa=fc and Ia=Ic
(c) fa=fb and Ia=Ib
(d) fa=fb  and Ia=Ib

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

Concept Questions :-

Einstein photo-electric equation
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