Light with an energy flux of 25 x 104 Wm-2 falls on a perfectly reflecting surface at normal incidence. If the surface area is 15cm2 the average force exerted on the surface is
(1)1.25x10-6N
(2)2.5x10-6N
(3)1.2x10-6N
(4)3.0x10-6N
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NEET MCQ Books for XIth & XIIth Physics, Chemistry & Biology
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
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NEET MCQ Books for XIth & XIIth Physics, Chemistry & Biology
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
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NEET MCQ Books for XIth & XIIth Physics, Chemistry & BiologyThe wavelength \(\lambda_{e}\) of an electron and \(\lambda_{p}\) of a photon of the same energy E are related as:
1.
2.
3.
4.
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NEET MCQ Books for XIth & XIIth Physics, Chemistry & BiologyA 200W sodium street lamp emits yellow light of wavelength 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)
(2)
(3)
(4)
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NEET MCQ Books for XIth & XIIth Physics, Chemistry & BiologyMonochromatic 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)
(2)
(3)
(4)
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NEET MCQ Books for XIth & XIIth Physics, Chemistry & BiologyAn 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.
2.
3.
4.
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NEET MCQ Books for XIth & XIIth Physics, Chemistry & BiologyIf 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.
4. 100p
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NEET MCQ Books for XIth & XIIth Physics, Chemistry & BiologyIn the Davisson and Germer experiment, the velocity of electrons emitted from the electron gun can be increased by
1. increasing the filament current
2. decreasing the filament current
3. decreasing the potential difference between the anode and filament
4. increasing the potential difference between the anode and filament
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NEET MCQ Books for XIth & XIIth Physics, Chemistry & BiologyA radioactive nucleus of mass M emits a photon
of frequency and the nucleus recoils. The recoil
energy will be:
(1)
(2) zero
(3) h
(4)
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NEET MCQ Books for XIth & XIIth Physics, Chemistry & Biology