A rectangular glass block of refractive index 1.5 has an air bubble trapped inside it as shown in the diagram. When seen from the surface AB, it appears to be 4 cm deep.
$A rectangular glass block of refractive index 1.5 has an air bubble trapped inside it as shown in the diagram. When seen from the surface AB, it appears to be 4 cm deep.ICSE 2025 Physics Solved Question Paper.$
(a) Calculate the actual depth of the air bubble from the surface AB.
(b) For which colour of light, blue or yellow, the apparent depth will be greater?
(c) Turning the glass block upside down, DOES NOT change the apparent depth of the air bubble. State True or False.

Question

A rectangular glass block of refractive index 1.5 has an air bubble trapped inside it as shown in the diagram. When seen from the surface AB, it appears to be 4 cm deep.
$A rectangular glass block of refractive index 1.5 has an air bubble trapped inside it as shown in the diagram. When seen from the surface AB, it appears to be 4 cm deep.ICSE 2025 Physics Solved Question Paper.$
(a) Calculate the actual depth of the air bubble from the surface AB.
(b) For which colour of light, blue or yellow, the apparent depth will be greater?
(c) Turning the glass block upside down, DOES NOT change the apparent depth of the air bubble. State True or False.

KnowledgeBoat · Accepted Answer

(a) Given, Refractive index of glass = 1.5 Apparent depth of air bubble = 4 cm As, So, actual depth of the air bubble from the surface AB is 6 cm. (b) As, Now, apparent depth will increase, if refractive index decreases and as wavelength increases, refractive index decreases. As wavelength of yellow light is greater than wavelength of blue light so, refractive index for yellow light is smaller than refractive index of blue light. Hence, for yellow light apparent depth will be greater. (c) When the block is turned upside down, then the real depth of the bubble is 15 – 6 = 9 cm And, So, the statement is false.

Physics

Refraction Plane Surfaces

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