Refraction of Light — Maharashtra (SSC) Class 10 Science Solutions (Free)
Free step-by-step Maharashtra (SSC) Class 10 Science solutions for "Refraction of Light" — important questions with detailed answers, download PDF for board exam preparation.
TL;DR: Free step-by-step Maharashtra (SSC) Class 10 Science solutions for "Refraction of Light" — important questions with detailed answers, download PDF for…
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Q1: Define refraction of light. State laws of refraction (Snell's law).
Refraction: Bending of light when it travels from one medium to another of different optical density. Laws: (1) Incident ray, refracted ray, and normal lie in same plane, (2) Snell's law: n1 sin(theta1) = n2 sin(theta2), where n is refractive index, theta is angle with normal. Light bends toward normal when entering denser medium (smaller angle), away from normal in rarer medium (larger angle). Refractive index = speed of light in vacuum / speed in medium.
Q2: Light travels from water (n=1.33) to air (n=1). If angle of incidence is 30 degrees, find angle of refraction.
Step 1: Given n1 = 1.33 (water), theta1 = 30 degrees, n2 = 1 (air)
Step 2: Use Snell's law: n1 sin(theta1) = n2 sin(theta2)
Step 3: 1.33 x sin(30) = 1 x sin(theta2)
Step 4: 1.33 x 0.5 = sin(theta2)
Step 5: sin(theta2) = 0.665, so theta2 = 41.6 degrees
Answer: Angle of refraction is 41.6 degrees. Light bends away from normal going from denser to rarer medium.
Q3: What is refractive index? Calculate refractive index of glass if light speed in glass is 2 x 10^8 m/s.
Refractive index: Ratio of speed of light in vacuum to speed of light in medium. Formula: n = c/v, where c = 3 x 10^8 m/s (speed in vacuum), v = speed in medium. Refractive index is dimensionless and always greater than 1 for denser media. Higher refractive index means light travels slower in that medium. Calculation: n = (3 x 10^8) / (2 x 10^8) = 1.5. Glass with n=1.5 is commonly used in lenses because it refracts light significantly.
Q4: Explain why a pencil in water appears bent when viewed from air.
When light from pencil travels from water (denser, n=1.33) to air (rarer, n=1), it refracts away from normal at the surface. Light undergoes refraction at water-air interface, bending away from normal. When this refracted light reaches our eye, our brain traces it backward assuming straight-line path, making the pencil appear bent or shifted. The apparent depth of water is less than actual depth due to this refraction. The amount of bending depends on angle of incidence and refractive indices of…
Q5: Define critical angle and total internal reflection.
Critical angle: Angle of incidence in a denser medium at which angle of refraction becomes 90 degrees in rarer medium. Formula: sin(theta_c) = n2/n1. For angle > critical angle, refracted ray doesn't exist; light is completely reflected back into the denser medium. Total internal reflection: Complete reflection of light back into medium when light travels from denser to rarer medium at angle greater than critical angle. No light escapes the denser medium. Used in fiber optics, diamonds (high …
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