Practice free Dual Nature of Matter and Radiation (Physics) NEET multiple-choice questions online with instant answers and detailed explanations. No login required.
Assertion : The specific charge for positive rays is a characteristic constant.
Reason : The specific charge depends on charge and mass of positive ions present in positive rays.
(b) Specific charge of a positive ion corresponding to one gas is fixed but it is different for different gases.
Assertion : In photoelectric effect, on increasing the intensity of light, both the number of electrons emitted and kinetic energy of each of them get increased but photoelectric current remains unchanged.
Reason : The photoelectric current depends only on wavelength of light.
(d) On increasing the intensity of incident light, the current in photoelectric cell will increase. The energy of the photons (hv) will, however not increase with increase in intensity, and hence the kinetic energy of the emitted electrons will not increase.
Assertion : In photoemissive cell inert gas is used.
Reason : Inert gas in the photoemissive cell gives greater current.
(a) The photoemissive cell may be evacuated contain an inert gas at low pressure. An inert gas in the cell gives greater current but causes a time lag in the response of the cell to very rapid changes of radiation which may make it unsuitable for some purpose.
A plane electromagnetic wave of wave intensity 6 W/ strikes a small mirror of area 30 , held perpendicular to the approaching wave. The momentum transferred in kg by the wave to the mirror each second will be
The momentum transferred per second = Force (F)
Bragg's law for X-rays is
Bragg's law for different of X-rays is
Assertion : Potassium and caesium are useful as electrodes in photoelectric cells.
Reason : Potassium and caesium, when irradiated with light, the light energy absorbed is sufficient to eject out the electron from an atom.
(A). Low ionisation energies of potassium and caesium.
Which of the following phenomena best describes the absorption of light by the rods and cones in the retina of the human eye?
According to the provided text, 'The gathering and focussing mechanism of light by the eye-lens is well described in the wave picture. But its absorption by the rods and cones (of the retina) requires the photon picture of light.' This directly indicates that the absorption by rods and cones involves the particle nature of light, i.e., photons.
The de Broglie hypothesis suggests that if radiation exhibits dual (wave-particle) nature, then particles of matter should also exhibit wave-like character. This hypothesis was based on the reasoning that:
The text states, 'He reasoned that nature was symmetrical and that the two basic physical entities – matter and energy, must have symmetrical character. If radiation shows dual aspects, so should matter.' This is the core reasoning behind de Broglie's hypothesis.
What is the relationship between the de Broglie wavelength ($\lambda$) associated with a moving particle and its momentum (p)?
The de Broglie relation is given as $\lambda = h/p$, where h is Planck's constant and p is the momentum of the particle. (Equation 11.5 in the text: $\lambda = h/p = h/mv$).
The acceptance of the particle or photon description of electromagnetic radiation was significantly influenced by the accurate confirmation of Einstein's photoelectric equation by:
The text mentions, 'Millikan’s first precise measurements confirmed the Einstein’s photoelectric equation and obtained an accurate value of Planck’s constant h. This led to the acceptance of particle or photon description (nature) of electromagnetic radiation, introduced by Einstein.'
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