When a body falls freely under gravity, which statement is correct? MCQ with Answer and Explanation
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Question #1
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Why does a metal spoon feel colder than a wooden spoon when left in a cold room, despite both being at the same room temperature?
Correct Answer: Option C
Explanation:
Both spoons are at the same temperature. However, metal is a good conductor of heat. When you touch it, it rapidly conducts heat away from your hand, making your skin feel a sudden drop in temperature (which you perceive as 'cold'). Wood is a poor conductor, so it draws heat from your hand very slowly.
Both spoons are at the same temperature. However, metal is a good conductor of heat. When you touch it, it rapidly conducts heat away from your hand, making your skin feel a sudden drop in temperature (which you perceive as 'cold'). Wood is a poor conductor, so it draws heat from your hand very slowly.
Question #2
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The gravitational constant G was first measured by
Question #3
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The phenomenon of dispersion of light occurs because:
Correct Answer: Option A
Explanation:
Dispersion (splitting of white light into colors) occurs because refractive index n varies with wavelength (Cauchy's relation: n ∝ 1/λ² approximately). Since v = c/n, different colors travel at different speeds in the medium, causing different refraction angles (Snell's law). Frequency remains constant across media. Memory tip: 'Dispersion: n(λ) ⇒ v(λ) ⇒ different bending; violet bends most (highest n)'. This optics concept is frequently tested in competitive exams. Always distinguish cause (speed variation) from property (frequency/wavelength); competitive exams often test this nuanced understanding.
Dispersion (splitting of white light into colors) occurs because refractive index n varies with wavelength (Cauchy's relation: n ∝ 1/λ² approximately). Since v = c/n, different colors travel at different speeds in the medium, causing different refraction angles (Snell's law). Frequency remains constant across media. Memory tip: 'Dispersion: n(λ) ⇒ v(λ) ⇒ different bending; violet bends most (highest n)'. This optics concept is frequently tested in competitive exams. Always distinguish cause (speed variation) from property (frequency/wavelength); competitive exams often test this nuanced understanding.
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