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Q1. If refractive index increases, speed of light in medium: Physics
Refractive index (n) is inversely proportional to the speed of light in a medium (n = c/v). So, when refractive index increases, the speed of light in that medium decreases. This is why light travels slower in denser media like glass and diamond.
Q2. Which medium has a refractive index around 1.52?
Crown glass has a refractive index of approximately 1.52. Alcohol has n ≈ 1.36, turpentine oil has n ≈ 1.47, and ice has n ≈ 1.31. Crown glass is commonly used in lenses and optical instruments.
Q3. A medium with refractive index 1.52 is:
Crown glass has a refractive index of about 1.52. Water has n ≈ 1.33, benzene has n ≈ 1.50, and ice has n ≈ 1.31. This makes crown glass optically denser than water and ice.
Q4. Optical density is not the same as:
Optical density refers to how much a medium slows down light (related to refractive index). It is not the same as mass density (mass per unit volume). A material can have high mass density but low optical density, or vice versa.
Q5. Light bends away from the normal when moving from:
When light moves from a denser medium (glass) to a rarer medium (air), it speeds up and bends away from the normal. In all other options, light moves from rarer to denser medium, so it bends towards the normal.
Q6. Which medium has refractive index 1.31?
Ice has a refractive index of approximately 1.31. Kerosene has n ≈ 1.44, alcohol has n ≈ 1.36, and water has n ≈ 1.33. Ice is optically rarer than water.
Q7. Bending of light at a boundary is called:
Refraction is the bending of light when it passes obliquely from one transparent medium to another at their boundary. This happens because the speed of light changes in different media.
Q8. Optically rarer medium means:
An optically rarer medium has a lower refractive index, meaning light travels faster in it. Air is an example of an optically rarer medium compared to water or glass.
Q9. When light enters a denser medium, it:
When light enters a denser medium (like air to glass), its speed decreases because the denser medium has a higher refractive index. This slowing down causes the light to bend towards the normal.
Q10. Which is an optically rarer medium?
Air is optically rarer than water, glass, and diamond because it has the lowest refractive index (approximately 1.0003). Light travels fastest in air compared to these other media.
Q11. Refractive index of a medium depends on:
Refractive index is the ratio of the speed of light in one medium to the speed in another medium. It depends on the speed of light in the two media, as well as the wavelength of light and temperature.
Q12. Optically denser medium means one with:
An optically denser medium has a higher refractive index, meaning light travels slower in it. Examples include glass, diamond, and water compared to air.
Q13. Which medium has refractive index 2.42?
Diamond has the highest refractive index among common materials, with n ≈ 2.42. Ruby has n ≈ 1.71, sapphire has n ≈ 1.77, and benzene has n ≈ 1.50. This high refractive index gives diamonds their sparkle.
Q14. The refractive index of medium 2 with respect to medium 1 is represented by:
The refractive index of medium 2 with respect to medium 1 is written as n₂₁. The first subscript (2) is the medium being entered, and the second (1) is the medium being left.
Q15. When light travels from one medium to another, its:
When light travels from one medium to another, its speed and direction may change (refraction). The frequency of light remains constant during refraction, while wavelength changes.
Q16. Dense flint glass has refractive index around:
Dense flint glass has a refractive index of approximately 1.65. This is higher than crown glass (1.52) and is used in high-quality lenses for better light bending.
Q17. A ray of light changes direction at the boundary because of:
Light changes direction (refracts) at the boundary between two media because its speed changes. This change in speed causes the light to bend. The frequency of light remains constant.
Q18. Optically denser medium always has:
An optically denser medium has a higher refractive index, meaning light travels slower in it. It is not necessarily related to mass density or transparency.
Q19. Benzene has a refractive index of:
Benzene has a refractive index of approximately 1.50. This is similar to crown glass and makes benzene optically denser than water (1.33) and alcohol (1.36).
Q20. If c is the speed of light in air and v in a medium, refractive index is:
The absolute refractive index (n) is the ratio of the speed of light in a vacuum (or air) to the speed of light in the medium. So, n = c/v. Since v is always less than c, n is always greater than 1.
Q21. Refractive index of water is approximately:
The refractive index of water is approximately 1.33. This means light travels 1.33 times slower in water than in a vacuum. This is why objects appear bent when seen through water.
Q22. The refractive index of air is approximately:
The refractive index of air is approximately 1.0003, which is very close to 1. For most practical calculations, the refractive index of air is taken as 1.00.
Q23. When light moves from denser to rarer medium, it:
When light moves from a denser medium to a rarer medium (like glass to air), it speeds up because the rarer medium has a lower refractive index. This causes the light to bend away from the normal.
Q24. Ruby has refractive index near:
Ruby has a refractive index of approximately 1.71. This is higher than glass (1.52) and water (1.33), making it optically denser. The high refractive index contributes to the gemstone’s brilliance.
Q25. Which is an example of optically denser medium than water?
Kerosene has a refractive index of about 1.44, which is higher than water (1.33). So, kerosene is optically denser than water. Ice (1.31), alcohol (1.36), and air (1.0003) are optically rarer than water.
Q26. Turpentine oil has refractive index:
Turpentine oil has a refractive index of approximately 1.47. This is higher than water (1.33) and alcohol (1.36), but lower than glass (1.52) and diamond (2.42).
Q27. Which is optically denser?
Kerosene has a refractive index of 1.44, which is higher than water’s refractive index of 1.33. Therefore, kerosene is optically denser than water. Light travels slower in kerosene than in water.
Q28. Which has a refractive index of 1.44?
Kerosene has a refractive index of approximately 1.44. Ice has n ≈ 1.31, water has n ≈ 1.33, and turpentine oil has n ≈ 1.47. Kerosene is optically denser than water and ice.
Q29. Light bends towards the normal when it travels from:
When light travels from a rarer medium (air) to a denser medium (glass), it slows down and bends towards the normal. In options B and C, light moves from denser to rarer, so it bends away from the normal.
Q30. Light travels faster in:
Light travels fastest in air (or vacuum) because air has the lowest refractive index. In turpentine oil, glass, and water, light travels slower due to their higher refractive indices.
Q31. If V₁ and V₂ are speeds of light in media 1 and 2 respectively, then n₂₁ =
The refractive index of medium 2 with respect to medium 1 (n₂₁) is the ratio of the speed of light in medium 1 (V₁) to the speed of light in medium 2 (V₂). So, n₂₁ = V₁/V₂.
Q32. The speed of light in vacuum is approximately:
The speed of light in a vacuum is approximately 3 × 10⁸ meters per second (more precisely, 299,792,458 m/s). This is the fastest speed at which light can travel.
Q33. The absolute refractive index is taken with respect to:
The absolute refractive index of a medium is taken with respect to a vacuum or air (for practical purposes). It compares the speed of light in air to the speed in the given medium.
Q34. Light bends more in a medium that is:
Light bends more in a medium that is more optically dense (higher refractive index). This is because the speed of light changes more significantly, causing greater refraction.
Q35. The refractive index represents which of the following?
Refractive index determines how much a ray of light changes direction when entering a medium. A higher refractive index means more bending of light.
Q36. The refractive index of sapphire is around:
Sapphire has a refractive index of approximately 1.77. This is higher than glass (1.52) and water (1.33), but lower than diamond (2.42). Sapphire is used in high-quality optical windows.
Q37. A ray of light slows down the most in:
Among the given options, glass has the highest refractive index (about 1.50), so light slows down the most in glass. In vacuum, light does not slow down at all (n = 1).
Q38. Fused quartz has refractive index:
Fused quartz has a refractive index of approximately 1.46. It is used in optical instruments because of its low thermal expansion and good light transmission properties.
Q39. The refractive index of alcohol is:
Alcohol (ethyl alcohol) has a refractive index of approximately 1.36. This is slightly higher than water (1.33) but lower than glass (1.52).
Q40. A medium with lower refractive index is:
A medium with a lower refractive index is called optically rarer. Light travels faster in such a medium. Examples include air and ice compared to water and glass.
Q41. The ability of a medium to refract light is expressed as its:
Optical density is a measure of how much a medium can refract light. It is directly related to the refractive index—higher optical density means more refraction and slower light speed.
Q42. The speed of light reduces considerably in:
The speed of light reduces considerably in glass (about 2 × 10⁸ m/s) compared to air and vacuum. In vacuum, light travels at its maximum speed of 3 × 10⁸ m/s.
Q43. The refractive index of carbon disulphide is:
Carbon disulphide has a refractive index of approximately 1.63. This is higher than glass (1.52) and water (1.33), making it optically denser.
Q44. Higher optical density implies:
Higher optical density means higher refractive index, which means light travels slower in that medium. This is why light slows down more in glass than in water.
Q45. In refraction, which remains constant?
During refraction, the frequency of light remains constant. The speed and wavelength change when light enters a different medium. This is because frequency is determined by the source of light.
Q46. Light travels fastest in which medium?
Light travels fastest in a vacuum, where its speed is approximately 3 × 10⁸ m/s. In water, glass, and alcohol, light slows down due to their higher refractive indices.
Q47. Optical density relates to:
Optical density is directly related to the refractive index of a medium. A medium with a higher refractive index has higher optical density and slows down light more.
Q48. Rock salt has refractive index of about:
Rock salt has a refractive index of approximately 1.54. It is used in infrared optics because it transmits infrared light well.
Q49. When light enters a rarer medium from a denser medium, it bends:
When light travels from a denser medium to a rarer medium, it speeds up and bends away from the normal. This is why a stick in water appears bent.
Q50. The medium with the highest refractive index in the table is:
Diamond has the highest refractive index among the given options, with n ≈ 2.42. Carbon disulphide has n ≈ 1.63, dense flint glass has n ≈ 1.65, and sapphire has n ≈ 1.77. Diamond’s high refractive index gives it its characteristic sparkle.