Dispersion through a Prism — Homi Bhabha Class 9 Physics MCQs with Solutions
Free Homi Bhabha Class 9 Physics Dispersion through a Prism MCQs with step-by-step solutions (8 questions). Part of Light & Optics. Practise online on Prepizo — no login needed.
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Questions with solutions
Q1 — Dispersion through a Prism · medium · theory
When white light passes through a glass prism, it splits into seven colours. This phenomenon is called:
A. refraction only
B. dispersion ✓ Correct
C. diffraction
D. reflection
Solution: Dispersion is the splitting of white light into its constituent colours (VIBGYOR).
Q2 — Dispersion through a Prism · hard · theory
When white light is dispersed by a prism, the colour that bends the least is:
A. blue
B. violet
C. green
D. red ✓ Correct
Solution: Red light has the longest wavelength and is deviated least; violet is deviated most.
Q3 — Dispersion through a Prism · medium · theory
A rainbow is formed by the dispersion of sunlight by:
A. the ozone layer
B. dust particles
C. tiny water droplets in the atmosphere ✓ Correct
D. clouds reflecting light
Solution: Water droplets act like tiny prisms, dispersing sunlight into a rainbow.
Q4 — Dispersion through a Prism · hard · theory
Different colours of light are dispersed by a prism because in glass they travel at:
A. infinite speed
B. different speeds and so bend by different amounts ✓ Correct
C. the speed of sound
D. the same speed
Solution: Each colour has a slightly different speed (and refractive index) in glass, so each bends by a different amount.
Q5 — Dispersion through a Prism · medium · theory
The correct order of colours in the visible spectrum (VIBGYOR) from the least deviated to the most deviated is:
A. Red, Orange, Yellow, Green, Blue, Indigo, Violet ✓ Correct
B. Violet, Indigo, Blue, Green, Yellow, Orange, Red
C. Blue, Green, Red, Yellow, Violet, Orange, Indigo
D. Red, Yellow, Orange, Blue, Green, Violet, Indigo
Solution: Red bends least and violet most, so from least to most deviated: R, O, Y, G, B, I, V.
Q6 — Dispersion through a Prism · easy · theory
When white light passes through a glass prism and splits into its component colours, this phenomenon is called:
A. Dispersion ✓ Correct
B. Reflection
C. Refraction
D. Diffraction
Solution: The splitting of white light into its seven constituent colours (VIBGYOR) as it passes through a prism is called dispersion, which happens because different colours bend by different amounts.
Q7 — Dispersion through a Prism · medium · theory
In the spectrum formed when white light passes through a prism, which colour is deviated (bent) the most?
A. Violet ✓ Correct
B. Yellow
C. Green
D. Red
Solution: Violet has the shortest wavelength and the largest refractive index in glass, so it slows down the most and bends the most. Red, with the longest wavelength, bends the least.
Q8 — Dispersion through a Prism · hard · theory
When white light passes through a prism, red light is deviated the least and violet the most. Which statement best explains why red deviates the least?
A. All colours travel at the same speed inside the glass
B. Red travels slower than violet inside the prism
C. Violet has a longer wavelength than red
D. Red has a longer wavelength and a smaller refractive index in glass, so it bends the least ✓ Correct
Solution: The amount a colour bends depends on the refractive index of the glass for that colour. Red has the longest wavelength and the smallest refractive index, so it slows least and deviates least. Red actually travels faster (not slower) than violet inside glass.