The time period of a mass-spring system depends on MCQ with Answer and Explanation
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Question #1
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An echo is heard after 2 seconds from a cliff. If speed of sound is 340 m/s, distance of cliff is
Correct Answer: Option C
Explanation:
Sound travels to cliff and back. Total distance = speed × time = 340 × 2 = 680 m. So distance to cliff = 680/2 = 340 m. Use formula d = (v × t)/2. Time for round trip. Minimum distance for echo 17 m (approx) for 0.1 s persistence.
Sound travels to cliff and back. Total distance = speed × time = 340 × 2 = 680 m. So distance to cliff = 680/2 = 340 m. Use formula d = (v × t)/2. Time for round trip. Minimum distance for echo 17 m (approx) for 0.1 s persistence.
Question #2
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Which of the following is true for a geostationary satellite?
Correct Answer: Option C
Explanation:
Geostationary satellite has orbital period equal to Earth's rotation (24 hours) and orbits in equatorial plane in same direction. It appears stationary from Earth's surface. Altitude about 36,000 km. Used for communication.
Geostationary satellite has orbital period equal to Earth's rotation (24 hours) and orbits in equatorial plane in same direction. It appears stationary from Earth's surface. Altitude about 36,000 km. Used for communication.
Question #3
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The energy of a photon is directly proportional to its:
Correct Answer: Option B
Explanation:
Photon energy E = hν, where h is Planck's constant, ν is frequency. Thus E ∝ ν. Since c = νλ, E = hc/λ, so E ∝ 1/λ (inversely proportional to wavelength). Amplitude relates to intensity (number of photons), not individual photon energy. Speed is constant (c) in vacuum. Memory aid: 'Higher frequency (shorter wavelength) photons have more energy (e.g., gamma > radio)'. This quantum physics concept is frequently tested in competitive exams. Always use E = hν for photon energy calculations; avoid confusing wave amplitude with photon energy.
Photon energy E = hν, where h is Planck's constant, ν is frequency. Thus E ∝ ν. Since c = νλ, E = hc/λ, so E ∝ 1/λ (inversely proportional to wavelength). Amplitude relates to intensity (number of photons), not individual photon energy. Speed is constant (c) in vacuum. Memory aid: 'Higher frequency (shorter wavelength) photons have more energy (e.g., gamma > radio)'. This quantum physics concept is frequently tested in competitive exams. Always use E = hν for photon energy calculations; avoid confusing wave amplitude with photon energy.
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