Critical Thinking Questions: Refraction of Light at Plane Surfaces

Type I

Assertion & Reason Based Questions

Q1: Assertion: Total internal reflection can occur when light travels from a denser to a rarer medium.
Reason: The angle of incidence in the denser medium must be greater than the critical angle for that medium for total internal reflection to occur.
(a) Both the assertion and the reason are true, and the reason is a correct explanation of the assertion. 
(b) The assertion is true, but the reason is false. 
(c) The assertion is false, but the reason is true. 
(d) Both the assertion and the reason are false.

Q2: Assertion: When light passes from a rarer to a denser medium, its frequency increases.
Reason: The speed of light is lower in a denser medium, which according to the relationship v = fλ, would increase the frequency if the wavelength decreases.
(a) Both the assertion and the reason are true, and the reason is a correct explanation of the assertion. 
(b) The assertion is true, but the reason is false.
(c) The assertion is false, but the reason is true. 
(d) Both the assertion and the reason are false.

Q3: Assertion: The emergent ray is parallel to the incident ray when light passes through a rectangular glass block.
Reason: The principle of reversibility of light indicates that paths of light are reversible, thus maintaining parallelism upon emergence.
(a) Both the assertion and the reason are true, and the reason is a correct explanation of the assertion. 
(b) The assertion is true, but the reason is false. 
(c) The assertion is false, but the reason is true. 
(d) Both the assertion and the reason are false.

Q4: Assertion: The refractive index of the material of the prism does not affect the angle of minimum deviation (δ_min).
Reason: The angle of minimum deviation is determined solely by the geometry of the prism and the wavelength of light used.
(a) Both the assertion and the reason are true, and the reason is a correct explanation of the assertion. 
(b) The assertion is true, but the reason is false. 
(c) The assertion is false, but the reason is true. 
(d) Both the assertion and the reason are false.

Q5: Assertion: The apparent depth of an object in water is greater than its real depth when viewed from above the water.
Reason: This is due to the refraction of light, as light travels slower in air than in water, making the object appear shallower than it really is.
(a) Both the assertion and the reason are true, and the reason is a correct explanation of the assertion. 
(b) The assertion is true, but the reason is false. 
(c) The assertion is false, but the reason is true. 
(d) Both the assertion and the reason are false.

Q6: Assertion: A stick appears bent when partially submerged in water due to the refractive index of water being different from that of air.
Reason: The refractive index of water is less than that of air, causing the light rays to bend away from the normal.
(a) Both the assertion and the reason are true, and the reason is a correct explanation of the assertion. 
(b) The assertion is true, but the reason is false. 
(c) The assertion is false, but the reason is true. 
(d) Both the assertion and the reason are false.

Q7: Assertion: The critical angle is the angle of incidence in the denser medium for which the angle of refraction in the rarer medium is 90°.
Reason: At the critical angle, light undergoes total internal reflection, not refraction.
(a) Both the assertion and the reason are true, and the reason is a correct explanation of the assertion. 
(b) Both the assertion and the reason are true, but the reason is not a correct explanation of the assertion. 
(c) The assertion is true, but the reason is false. 
(d) The assertion is false, but the reason is true.

Q8: Assertion: The critical angle of incidence increases with an increase in the wavelength of light.
Reason: For a given pair of media, the critical angle is determined by the ratio of the velocities of light in the two media.
(a) Both the assertion and the reason are true, and the reason is a correct explanation of the assertion. 
(b) Both the assertion and the reason are true, but the reason is not a correct explanation of the assertion. 
(c) The assertion is true, but the reason is false. 
(d) The assertion is false, but the reason is true.

Q9: Assertion: Total internal reflection cannot occur when light travels from a denser to a rarer medium.
Reason: Total internal reflection requires the light to travel from a medium with a higher refractive index to one with a lower refractive index.
(a) Both the assertion and the reason are true, and the reason is a correct explanation of the assertion. 
(b) The assertion is true, but the reason is false. 
(c) The assertion is false, but the reason is true. 
(d) Both the assertion and the reason are false.

Q10: Assertion: In a prism where each angle is 60°, such as an equilateral prism, the light ray does not suffer total internal reflection inside the prism and gets refracted as it exits.
Reason: The critical angle for glass-air interface is less than 60°, and hence the angle of incidence will always be greater than the critical angle, leading to total internal reflection.
(a) Both the assertion and the reason are true, and the reason is a correct explanation of the assertion. 
(b) The assertion is true, but the reason is false. 
(c) The assertion is false, but the reason is true. 
(d) Both the assertion and the reason are false.

Type II

Statements Based Questions

Q11: Statement 1: When light passes from a rarer to a denser medium, its speed decreases. 
Statement 2: The frequency of light remains unchanged when it passes from air to water. 
Statement 3: The wavelength of light increases when it passes from glass to air.
(a) Only 1 
(b) Only 2 
(c) Only 1 and 2 
(d) All 1, 2, and 3

Q12: Statement 1: The refractive index of water with respect to air is 4/3. 
Statement 2: The refractive index of glass with respect to air is 3/2. 
Statement 3: The refractive index of diamond is greater than that of glass.
(a) Only 2 
(b) Only 1 and 3 
(c) Only 2 and 3 
(d) All 1, 2, and 3

Q13: Statement 1: Total internal reflection occurs when light passes from a denser to a rarer medium. 
Statement 2: The critical angle is dependent on the wavelength of light. 
Statement 3: Total internal reflection can only occur if the angle of incidence is greater than the critical angle.
(a) Only 1 and 3 
(b) Only 2 
(c) Only 1 
(d) All 1, 2, and 3

Q14: Statement 1: The principle of reversibility of light implies that the path of light is reversible. 
Statement 2: Snell's Law can be used to calculate the refractive index of a medium. 
Statement 3: Lateral displacement of light occurs due to refraction through a glass slab.
(a) Only 1 and 2 
(b) Only 3 
(c) Only 1 and 3 
(d) All 1, 2, and 3

Q15: Statement 1: Refractive index decreases with an increase in the wavelength of light. 
Statement 2: Violet light bends more than red light when passing from air to glass. 
Statement 3: The refractive index of glass is the same for all colours of light.
(a) Only 1 and 2 
(b) Only 1 
(c) Only 2 and 3 
(d) All 1, 2, and 3

Q16: Statement 1: Light speed in diamond is more than in glass. 
Statement 2: The refractive index is a ratio of the speed of light in vacuum to that in the medium. 
Statement 3: Diamond has a higher refractive index than water.
(a) Only 1 
(b) Only 2 and 3 
(c) Only 1 and 3 
(d) All 1, 2, and 3

Q17: Statement 1: If the speed of light in air is (3 × 10⁸ m/s) and in glass is (2 × 10⁸ m/s), the refractive index of glass is 1.5. 
Statement 2: The speed of light in water with refractive index 4/3 is (2.25 × 10⁸ m/s). 
Statement 3: The refractive index of diamond is 2.41, thus light travels in diamond at (1.245 × 10⁸ m/s).
(a) Only 1 and 2 
(b) Only 3 
(c) Only 1 and 3 
(d) All 1, 2, and 3

Q18: Statement 1: Lateral displacement of a ray of light through a glass slab increases with the increase in the angle of incidence. 
Statement 2: The emergent ray is always parallel to the incident ray in a rectangular glass slab. 
Statement 3: The refractive index of water is approximately 1.33.
(a) Only 1 and 2 
(b) Only 2 and 3 
(c) Only 1 and 3 
(d) All 1, 2, and 3

Q19: Statement 1: When light moves from a denser to a rarer medium, it bends away from the normal. 
Statement 2: Snell's law is represented by the equation sin i = sin r. 
Statement 3: The angle of incidence is always equal to the angle of refraction.
(a) Only 1 
(b) Only 1 and 2 
(c) Only 2 and 3 
(d) All 1, 2, and 3

Q20: Statement 1: The critical angle is the angle of incidence for which the angle of refraction is 90°. 
Statement 2: Total internal reflection can only occur when light moves from a denser to a rarer medium. 
Statement 3: The refractive index is inversely proportional to the critical angle.
(a) Only 1 and 2 
(b) Only 2 and 3 
(c) Only 1 and 3 
(d) All 1, 2, and 3