The working principle of an electric generator is:
A. Heating effect of current
B. Chemical effect of current
C. Magnetic effect of current
D. Electromagnetic induction
Answer: Option D
Solution (By JKExamLibrary)
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:
Fraction of volume submerged = ρ_ice / ρ_water. If 1/10 above, 9/10 submerged. So ρ_ice/ρ_water = 9/10 => ρ_ice = 0.9 g/cm³. Density of ice is 0.9 g/cm³.
Explanation:
According to Newton's Second Law of Motion, the rate of change of momentum is directly proportional to the applied unbalanced force. Rate of change of momentum = Force = mass × acceleration. Force = 2 kg × 5 m/s² = 10 Newtons (N). Note that '10 kg m/s' is a unit of momentum, not its rate of change.
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