Which of the following statements is correct? (1) A very small opaque object does not change the straight path of light. (2) Convex mirrors are generally used in torches. (3) The mass density of kerosene is less than that of water. (4) The ability of a medium to reflect light is expressed as optical density.
Question:
Which of the following statements is correct? (1) A very small opaque object does not change the straight path of light. (2) Convex mirrors are generally used in torches. (3) The mass density of kerosene is less than that of water. (4) The ability of a medium to reflect light is expressed as optical density.
Which of the following statements is correct? (1) A very small opaque object does not change the straight path of light. (2) Convex mirrors are generally used in torches. (3) The mass density of kerosene is less than that of water. (4) The ability of a medium to reflect light is expressed as optical density.
Options
Answer: (3) The mass density of kerosene is less than that of water
Explanation:
Statement (3) is correct. The density of kerosene is approximately 0.80 g/cm³, which is less than the density of water (1.00 g/cm³), which is why kerosene floats on water. Statement (1) is incorrect — even small opaque objects obstruct light (causing diffraction). Statement (2) is incorrect — concave mirrors (not convex) are used in torches and headlights to produce a parallel beam of light. Statement (4) is incorrect — optical density refers to the ability of a medium to refract (bend) light, not to reflect it; the refractive index measures this property.
Explanation:
Statement (3) is correct. The density of kerosene is approximately 0.80 g/cm³, which is less than the density of water (1.00 g/cm³), which is why kerosene floats on water. Statement (1) is incorrect — even small opaque objects obstruct light (causing diffraction). Statement (2) is incorrect — concave mirrors (not convex) are used in torches and headlights to produce a parallel beam of light. Statement (4) is incorrect — optical density refers to the ability of a medium to refract (bend) light, not to reflect it; the refractive index measures this property.
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