The unit of power, watt, is equivalent to MCQ with Answer and Explanation

The unit of power, watt, is equivalent to
A. N m
B. J/s
C. N/s
D. J s
Answer: Option B
Solution (By JKSSB Mock Tests)
Watt = joule per second.

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Practice More Physics Questions

Question #1
In standard AC household supply in India, the frequency of the alternating current is 50 Hz. How many times per second does the current change its direction?
A. 50 times
B. 100 times
C. 0 times
D. 25 times

Correct Answer: Option B


Explanation:
A frequency of 50 Hz means there are 50 complete wave cycles per second. A single complete sinusoidal cycle consists of one positive half-cycle and one negative half-cycle. Therefore, the current reaches zero and reverses its direction exactly twice during each complete cycle. For 50 cycles, the current changes direction 50 * 2 = 100 times per second.

This question belongs to: Science Physics
Question #2
The law of conservation of energy states that
A. Energy can neither be created nor destroyed, only transformed
B. Energy can be created but not destroyed
C. Total energy always increases
D. Energy can be destroyed but not created

Correct Answer: Option A


Explanation:
First law of thermodynamics: Energy is conserved in an isolated system. It changes forms (kinetic to potential etc.) but total constant. Perpetual motion machine impossible.

This question belongs to: Science Physics
Question #3
The force between two charges is 10 N in vacuum. If a dielectric of constant 5 is inserted, force becomes
A. 10 N
B. 0.5 N
C. 50 N
D. 2 N

Correct Answer: Option D


Explanation:
F_medium = F_vacuum / K = 10/5 = 2 N.

This question belongs to: Science Physics