Which of the following is true for a geostationary satellite?
A. Its orbital period is 12 hours
B. It revolves opposite to Earth's rotation
C. It appears fixed relative to a point on Earth
D. Its orbit is at any altitude
Answer: Option C
Solution (By JKSSB Mock Tests)
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.
Explanation:
Electric generators convert mechanical energy to electrical energy using electromagnetic induction: rotating a coil in magnetic field (or vice versa) induces EMF due to changing magnetic flux. This is Faraday's law application. Motors use the reverse principle (force on current-carrying conductor in field). Memory tip: 'Generator: motion ⇒ electricity (induction); Motor: electricity ⇒ motion (force)'. This application question tests understanding of device principles, common in competitive exams. Always distinguish generator (induction) from motor (Lorentz force) operation.
Explanation:
T = 2π√(m/k): depends on mass and spring constant only, not gravity. Weightlessness doesn't affect spring force. Memory aid: 'Spring period: independent of g; pendulum period: depends on g'. Oscillations concept frequently tested in competitive exams.
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