The heating effect of electric current is described by: MCQ with Answer and Explanation

The heating effect of electric current is described by:
A. Ohm's law
B. Joule's law
C. Faraday's law
D. Lenz's law
Answer: Option B
Solution (By JKSSB Mock Tests)
Joule's law states that heat produced H = I²Rt, where I is current, R resistance, t time. This quantifies electrical energy converted to thermal energy in resistors. Ohm's law relates V, I, R; Faraday's and Lenz's laws concern electromagnetic induction. Memory aid: 'Joule heating ∝ I²R'. This definition-based question tests knowledge of fundamental laws in electricity, commonly examined in competitive exams. Applications include electric heaters, fuses, and incandescent bulbs. Always distinguish Joule's law (heating) from power formulas (P=VI=I²R=V²/R).

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Practice More Physics Questions

Question #1
The specific charge (e/m) of an electron was first measured by:
A. Rutherford
B. Bohr
C. Thomson
D. Millikan

Correct Answer: Option C


Explanation:
J. J. Thomson measured the specific charge (e/m) of electrons in 1897 using cathode ray tube experiments with electric and magnetic fields. Millikan later measured the charge e (oil drop experiment), allowing mass calculation. Rutherford discovered nucleus; Bohr developed atomic model. Memory aid: 'Thomson = e/m; Millikan = e'. This history-based question tests knowledge of experimental physics milestones, frequently appearing in competitive exams. Always link scientists to their specific measurements: Thomson (e/m), Millikan (e), Chadwick (neutron).

This question belongs to: Science Physics
Question #2
In an electric circuit, ammeter is connected in
A. Across load
B. Parallel
C. Either
D. Series

Correct Answer: Option D


Explanation:
Ammeter must be in series to measure full current. Very low internal resistance.

This question belongs to: Science Physics
Question #3
If a stone is dropped from a balloon rising upwards with a velocity of 10 m/s at a height of 75 m, what is the initial velocity of the stone relative to the ground?
A. 9.8 m/s downwards
B. 10 m/s downwards
C. 0 m/s
D. 10 m/s upwards

Correct Answer: Option D


Explanation:
Due to the inertia of motion, when an object is dropped from a moving vehicle (or balloon), it inherits the instantaneous velocity of that vehicle. Since the balloon was moving upwards at 10 m/s, the stone's initial velocity relative to the ground is 10 m/s upwards. It will rise slightly before falling.

This question belongs to: Science Physics