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ICSE Class 10 Physics Question 19 of 27

Solved Sample Paper 2 — Question 3

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Question

Question 4(iii)

(a) The velocity of light in diamond is 121000 km/s. What is its refractive index?

(b) With the help of a labelled diagram, show that the apparent depth of an object such as a coin in water is less than its real depth.

Answer

(a) Given,

velocity of light in diamond = 121000 kms-1

To convert kms-1 into ms-1, we multiply by 1000

121000 x 1000 ms-1 = 121 x 106 ms-1

Speed of light in air, c = 3 × 108 ms-1

As we know,

μ=Speed of light in vacuum or air (c) Speed of light in diamond (V)μ = \dfrac{\text{Speed of light in vacuum or air (c) }}{\text {Speed of light in diamond (V)}} \\[0.5em]

Substituting the values in the formula above we get,

μ=3×108121×106μ=3×1081.21×108μ=2.48μ = \dfrac{ 3 \times 10^8 } {121 \times 10^6} \\[0.5em] μ = \dfrac{ 3 \times 10^8 } {1.21 \times 10^8} \\[0.5em] μ = 2.48 \\[0.5em]

Hence, refractive index = 2.48

(b) Below labelled diagram, shows that the apparent depth of a coin in water is less than its real depth:

With the help of a labelled diagram, show that the apparent depth of an object such as a coin in water is less than its real depth. Physics Sample Paper Solved ICSE Class 10.