Newton's Corpuscular Theory — NEET Physics MCQs with Solutions
Free NEET Physics Newton's Corpuscular Theory MCQs with step-by-step solutions (15 questions). Part of Wave Theory of Light. Practise online on Prepizo — no login needed.
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Questions with solutions
Q1 — Newton's Corpuscular Theory · easy · theory
According to Newton's corpuscular theory, light consists of:
A. Tiny, weightless, perfectly elastic particles (corpuscles) travelling in straight lines ✓ Correct
B. Transverse electromagnetic waves
C. Discrete energy packets called photons
D. Longitudinal mechanical waves in a medium
Solution: Newton proposed that a luminous body emits streams of minute, elastic corpuscles that travel in straight lines at high speed.
Q2 — Newton's Corpuscular Theory · easy · theory
Newton's corpuscular theory could satisfactorily explain:
A. Reflection and rectilinear propagation of light ✓ Correct
B. Polarisation of light
C. Interference of light
D. Diffraction of light
Solution: The corpuscular theory explained rectilinear propagation and reflection (as elastic rebound), but failed for interference, diffraction and polarisation.
Q3 — Newton's Corpuscular Theory · medium · theory
To explain refraction of light into a denser medium, Newton's corpuscular theory required that the speed of light in the denser medium be:
A. Greater than in the rarer medium ✓ Correct
B. Less than in the rarer medium
C. Zero
D. Equal to that in the rarer medium
Solution: Newton assumed corpuscles are attracted towards the denser medium, increasing their velocity — so light should travel faster in a denser medium. This prediction was later proved wrong.
Q4 — Newton's Corpuscular Theory · medium · theory
The prediction of Newton's corpuscular theory that light travels faster in a denser medium was experimentally disproved by:
A. Foucault's measurement of the speed of light in water ✓ Correct
B. Young's double-slit experiment
C. Millikan's oil-drop experiment
D. Hertz's experiment
Solution: Foucault showed that light travels slower in water (denser) than in air, contradicting the corpuscular prediction and supporting the wave theory.
Q5 — Newton's Corpuscular Theory · medium · theory
In Newton's corpuscular theory, the different colours of light were attributed to:
A. Different frequencies of vibration
B. Different numbers of photons
C. Different wavelengths of a wave
D. Corpuscles of different sizes ✓ Correct
Solution: Newton explained colour by proposing that corpuscles of different sizes produce the sensation of different colours.
Q6 — Newton's Corpuscular Theory · medium · theory
Which phenomenon CANNOT be explained by the corpuscular theory of light?
A. Rectilinear propagation
B. Reflection
C. Interference ✓ Correct
D. Formation of shadows
Solution: Interference (and diffraction and polarisation) are wave phenomena that the particle-based corpuscular theory cannot account for.
Q7 — Newton's Corpuscular Theory · medium · theory
A strong point in favour of Newton's corpuscular theory in his time was that it easily explained:
A. The bending of light around small obstacles
B. The polarisation of reflected light
C. The coloured fringes in thin films
D. Why light travels in straight lines and casts sharp shadows ✓ Correct
Solution: Particles travelling in straight lines naturally explain rectilinear propagation and sharp shadows, which is why the theory was widely accepted for a long time.
Q8 — Newton's Corpuscular Theory · medium · theory
One reason Newton rejected the wave theory of light in favour of corpuscles was that:
A. Light could not travel through vacuum as a particle
B. Waves could not carry energy
C. Corpuscles explained interference better than waves
D. Waves were expected to bend around obstacles, yet light appeared to travel in straight lines ✓ Correct
Solution: Newton argued that if light were a wave it should bend appreciably around obstacles (diffraction), whereas light seemed to travel strictly in straight lines — so he preferred corpuscles.
Q9 — Newton's Corpuscular Theory · medium · theory
According to the corpuscular theory, reflection of light occurs because the corpuscles:
A. Undergo perfectly elastic collisions with the surface ✓ Correct
B. Slow down and reverse due to the medium
C. Are absorbed and re-emitted as waves
D. Interfere destructively at the surface
Solution: Reflection was explained as the elastic rebound of corpuscles from a surface, like a perfectly elastic ball bouncing off a wall.
Q10 — Newton's Corpuscular Theory · medium · theory
The corpuscular theory was finally abandoned mainly because it:
A. Could not explain the rectilinear propagation of light
B. Predicted a higher speed of light in denser media and could not explain interference, diffraction and polarisation ✓ Correct
C. Required light to have zero speed in vacuum
D. Could not explain reflection of light
Solution: Its wrong prediction about the speed of light in denser media (disproved by Foucault) together with its failure to explain interference, diffraction and polarisation led to its rejection.
Q11 — Newton's Corpuscular Theory · medium · numerical
For a medium in which sin i / sin r = 1.5, the corpuscular theory predicts the speed of light in the medium (c = 3 × 10⁸ m/s) to be:
A. 1.5 × 10⁸ m/s
B. 2 × 10⁸ m/s
C. 3 × 10⁸ m/s
D. 4.5 × 10⁸ m/s ✓ Correct
Solution: Corpuscular theory (wrongly) predicts v_medium/v_vacuum = sin i/sin r = 1.5, so v = 1.5 × 3 × 10⁸ = 4.5 × 10⁸ m/s — faster than in vacuum, later disproved by Foucault.
Q12 — Newton's Corpuscular Theory · medium · numerical
A ray enters a medium with angle of incidence 53° and refraction 30° (sin53° = 0.8, sin30° = 0.5). The corpuscular prediction for v_medium/v_vacuum is:
A. 1.6 ✓ Correct
B. 0.625
C. 0.8
D. 1.0
Solution: Corpuscular: v_medium/v_vacuum = sin i/sin r = 0.8/0.5 = 1.6 (predicts speeding up — incorrect).
Q13 — Newton's Corpuscular Theory · hard · numerical
For water (n = 4/3), the ratio of the corpuscular-predicted speed to the actual (wave-theory) speed of light in water is:
A. 16 : 9 ✓ Correct
B. 9 : 16
C. 1 : 1
D. 4 : 3
Solution: Corpuscular predicts v_w/v_air = 4/3; the true value is 3/4. Ratio = (4/3)/(3/4) = 16/9.
Q14 — Newton's Corpuscular Theory · medium · numerical
Corpuscular theory predicts, for a glass of n = 1.5, a light speed in glass of (c = 3 × 10⁸ m/s):
A. 3 × 10⁸ m/s
B. 1 × 10⁸ m/s
C. 2 × 10⁸ m/s (correct)
D. 4.5 × 10⁸ m/s (wrong) ✓ Correct
Solution: It sets v = nc = 1.5 × 3 × 10⁸ = 4.5 × 10⁸ m/s. Wave theory correctly gives v = c/n = 2 × 10⁸ m/s.
Q15 — Newton's Corpuscular Theory · hard · numerical
If the angle of incidence is 60° and the corpuscular-predicted speed ratio v₂/v₁ is √3, the angle of refraction is (sin60° = √3/2):
A. 20°
B. 60°
C. 30° ✓ Correct
D. 45°
Solution: sin i/sin r = v₂/v₁ = √3 ⇒ sin r = sin60°/√3 = (√3/2)/√3 = 1/2 ⇒ r = 30°.