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NEET UG Dual Nature of Radiation and Matter — practice questions

Explore 161 free Dual Nature of Radiation and Matter questions in NEET UG Physics. Open each question or exercise to read its content, reference answers and available explanation.

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Dual Nature of Radiation and Matter questions and exercises with answers

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Light enters a glass slab (n = 1.5) at angle i = 30°. The angle of refraction r inside glass is approximately:Read the answer and worked solution →For two equal-amplitude coherent sources, the maximum and minimum intensities are:Read the answer and worked solution →In a photoelectric experiment, the minimum negative potential applied to the collector plate at which the photocurrent just drops to zero is called theRead the answer and worked solution →The momentum carried by a photon of wavelength $\lambda$ isRead the answer and worked solution →NEET · Physics · Photoelectric — Spot the ErrorRead the answer and worked solution →The specific charge (e/m) of the electron, determined by J. J. Thomson, is approximatelyRead the answer and worked solution →Millikan's oil-drop experiment established thatRead the answer and worked solution →The work function φ₀ of a metal is best defined asRead the answer and worked solution →1 electron-volt (eV) equalsRead the answer and worked solution →The stopping potential V₀ at a given frequency of incident light isRead the answer and worked solution →The K_max of the emitted photoelectron is related to the stopping potential V₀ byRead the answer and worked solution →Metals like Li, Na, K and Cs are photosensitive even to visible light because theyRead the answer and worked solution →If the frequency of incident light is doubled while the intensity is halved, the number of photoelectrons emitted per secondRead the answer and worked solution →The threshold frequency ν₀ for a metal is related to its work function byRead the answer and worked solution →Cathode rays were first identified byRead the answer and worked solution →An electron accelerated through 100 V has kinetic energy (in eV) equal toRead the answer and worked solution →Intensity or frequencyRead the answer and worked solution →Place the discoveriesRead the answer and worked solution →Who did whatRead the answer and worked solution →Type the quantum termRead the answer and worked solution →Pop the ultraviolet metalsRead the answer and worked solution →One word is wrongRead the answer and worked solution →Order the argumentRead the answer and worked solution →Radiation and matterRead the answer and worked solution →Which one does not belongRead the answer and worked solution →Does it change the energyRead the answer and worked solution →Spot the false statementRead the answer and worked solution →The minimum energy needed to free an electron from a metal is its:Read the answer and worked solution →Work function is usually measured in:Read the answer and worked solution →Photoelectric emission was discovered in 1887 by:Read the answer and worked solution →

Worked practice questions

Light enters a glass slab (n = 1.5) at angle i = 30°. The angle of refraction r inside glass is approximately:

  1. 30°
  2. 19.5°
  3. 45°
  4. 60°
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Correct answer: B. 19.5°

**Snell:** 1 × sin 30° = 1.5 × sin r → sin r = 0.5 / 1.5 = 0.333 → r = arcsin(0.333) ≈ **19.47°**. Light bends toward the normal (denser medium).

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For two equal-amplitude coherent sources, the maximum and minimum intensities are:

  1. I_max = I₁ + I₂; I_min = I₁ − I₂
  2. I_max = 4 I₀, I_min = 0 (perfect contrast)
  3. I_max = 2 I₀, I_min = I₀
  4. I_max = I_min = 2 I₀
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Correct answer: B. I_max = 4 I₀, I_min = 0 (perfect contrast)

Equal-amplitude coherent sources (I₁ = I₂ = I₀): **I_max = 4 I₀** (constructive), **I_min = 0** (destructive). **For unequal amplitudes:** I_max = (√I₁ + √I₂)², I_min = (√I₁ − √I₂)². **Contrast ratio** = (I_max − I_min)/(I_max + I_min) = 1 only when I₁ = I₂.

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In a photoelectric experiment, the minimum negative potential applied to the collector plate at which the photocurrent just drops to zero is called the

  1. saturation potential
  2. threshold potential
  3. stopping potential
  4. ionisation potential
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Correct answer: C. stopping potential

1. syllabus defines the relevant potentials. The collector plate $A$ is gradually made more negative with respect to the emitter $C$. 2. As the retarding voltage grows, slower photoelectrons cannot reach $A$, so the photocurrent falls. 3. The minimum retarding potential $V_0$ at which even the MOST energetic photoelectrons are just turned back, and the current becomes zero, is the STOPPING potential. 4. Option A (saturation) is the OPPOSITE limit, the positive potential at which all emitted electrons are collected. Threshold (B) refers to a frequency, not a potential. Ionisation potential (D) is an atomic-physics quantity unrelated to surface photoemission. _Source: syllabus Physics Part 2, Ch 11 "Dual Nature of Radiation and Matter", §11.4.2, p. 4 ¶3._

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