A photoelectric surface is illuminated successively by monochromatic light of wavelengths λ and 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 will be:
(h = Planck’s constant, c = speed of light)

1. hc/2λ

2. hc/λ

3. 2hc/λ

4. hc/3λ

Subtopic:  Einstein's Photoelectric Equation |
 71%
From NCERT
NEET - 2015
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Light with a wavelength of 500 nm is incident on a metal with a work function of 2.28 eV. The de Broglie wavelength of the emitted electron will be:
1. \( <2.8 \times 10^{-10} \mathrm{~m} \)
2. \( <2.8 \times 10^{-9} \mathrm{~m} \)
3. \( \geq 2.8 \times 10^{-9} \mathrm{~m} \)
4. \( <2.8 \times 10^{-12} \mathrm{~m}\)

Subtopic:  De-broglie Wavelength |
 60%
From NCERT
NEET - 2015
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Light with an energy flux of \(25\times 10^{4}~\text{Wm}^{-2}\) falls on a perfectly reflecting surface at normal incidence. If the surface area is \(15~\text{m}^2\), then the average force exerted on the surface is:
1. \(1.25\times 10^{-6}~\text{N}\)
2. \(2.5\times 10^{-6}~\text{N}\)
3. \(1.2\times 10^{-6}~\text{N}\)
4. \(3.0\times 10^{-6}~\text{N}\)

Subtopic:  Particle Nature of Light |
 62%
NEET - 2014
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When the energy of the incident radiation is increased by 20%, the kinetic energy of the photoelectrons emitted from a metal surface increases from 0.5 eV to 0.8 eV. The work function of the metal will be:
1. 0.65 eV

2. 1.0 eV

3. 1.3 eV

4. 1.5 eV

Subtopic:  Einstein's Photoelectric Equation |
 68%
From NCERT
NEET - 2014
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What will be the percentage change in the de-Broglie wavelength of the particle if the kinetic energy of the particle is increased to 16 times its previous value?
1. 25
2. 75
3. 60
4. 50

Subtopic:  De-broglie Wavelength |
 69%
From NCERT
NEET - 2014
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The wavelength \(\lambda_{e}\) of an electron and \(\lambda_{p}\) of a photon of the same energy E are related as:

1. λpλe2

2. λpλe 

3. λpλe

4. λp1λe

Subtopic:  De-broglie Wavelength |
 54%
From NCERT
NEET - 2013
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A 200W sodium street lamp emits yellow light of wavelength 0.6 μm. Assuming it to be 25% efficient in converting electrical energy to light, the number of photons of yellow light it emits per second is 

(1) 1.5×1020                               

(2) 6×1018

(3) 62×1020                                 

(4) 3×1019

Subtopic:  Electron Emission |
 69%
From NCERT
NEET - 2012
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Monochromatic radiation emitted when electron on hydrogen atom jumps from first excited to the ground state irradiates a photosensitive material. The stopping potential is measured to be 3.57 V.The threshold frequency of the material is:

(1)4×1015Hz                               

(2)5×1015Hz

(3)1.6×1015Hz                           

(4)2.5×1015Hz

Subtopic:  Einstein's Photoelectric Equation |
 64%
From NCERT
NEET - 2012
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An \(\alpha -\) particle moves in a circular path of radius 0.83 cm in the presence of a magnetic field of \(0.25 \mathrm{~Wb} / \mathrm{m}^2\). The de-Broglie wavelength associated with the particle will be:

1. \(1~\mathring {\text{A}}\) 2. \(0.1~\mathring {\text{A}}\)
3. \(10~\mathring {\text{A}}\) 4. \(0.01~\mathring {\text{A}}\)
Subtopic:  De-broglie Wavelength |
 57%
From NCERT
NEET - 2012
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If the momentum of an electron is changed by p, then the de-Broglie wavelength associated with it changes by 0.5%. What is the initial momentum of the electron?

1. 200p

2. 400p

3. p200

4. 100p

Subtopic:  De-broglie Wavelength |
 60%
From NCERT
NEET - 2012
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