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CBSE Class 10 Science Question 46 of 60

Solved 2022 Term 1 Question Paper CBSE Class 10 Science — Question 22

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Question 46

The refractive index of medium A is 1.5 and that of medium B is 1.33. If the speed of light in the air is 3 × 108 m/s, what is the speed of light in medium A and B respectively?

(a) 2 × 108 m/s and 1.33 × 108 m/s

(b) 1.33 × 108 m/s and 2 × 108 m/s

(c) 2.25 × 108 m/s and 2 × 108 m/s

(d) 2 × 108 m/s and 2.25 × 108 m/s

Answer

2 × 108 m/s and 2.25 × 108 m/s

Reason — We know,

refractive index of medium = speed of light in airspeed of light in medium\dfrac{\text{speed of light in air}}{\text{speed of light in medium}}

Substituting we get,

For medium A,

1.5 = 3×108speed of light in medium A\dfrac{3 \times 10^8}{\text{speed of light in medium A}}

speed of light in medium A = 3×1081.5\dfrac{3 \times 10^8}{1.5}

Hence, speed of light in medium A = 2 × 108 m/s

For medium B,

1.33 = 3×108speed of light in medium B\dfrac{3 \times 10^8}{\text{speed of light in medium B}}

speed of light in medium B = 3×1081.33\dfrac{3 \times 10^8}{1.33}

Hence, speed of light in medium B =2.25 × 108 m/s