Ohm's law is valid for MCQ with Answer and Explanation

Ohm's law is valid for
A. Semiconductors only
B. Electrolytes
C. Metallic conductors at constant temperature
D. All conductors
Answer: Option C
Solution (By JKExamLibrary)
Ohm's law V = IR holds for ohmic conductors (metals) provided temperature and physical conditions constant. Non-ohmic: semiconductors, diodes, electrolytes. Graph V-I is straight line for ohmic. Temperature changes resistance, so condition necessary.

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Practice More Physics Questions

Question #1
The process of adding impurity to a semiconductor is called
A. Sintering
B. Annealing
C. Doping
D. Purification

Correct Answer: Option C


Explanation:
Doping increases conductivity.

This question belongs to: Science Physics
Question #2
Transformer turns ratio N_p:N_s = 1:5. If V_p = 100V, V_s is:
A. 100V
B. 500V
C. 20V
D. 2500V

Correct Answer: Option B


Explanation:
V_s/V_p = N_s/N_p ⇒ V_s = 100×(5/1) = 500V. Step-up transformer increases voltage. Memory aid: 'Turns ratio = voltage ratio; current ratio inverse'. Direct transformer formula application frequently tested in competitive exams with ratio calculations.

This question belongs to: Science Physics
Question #3
The frequency of a sound wave is 200 Hz. Its time period is
A. 0.02 s
B. 200 s
C. 0.05 s
D. 0.005 s

Correct Answer: Option D


Explanation:
Time period T = 1/f = 1/200 = 0.005 s = 5 ms. Frequency is number of cycles per second. Relationship T = 1/f is fundamental. For 200 Hz, period is 5 milliseconds.

This question belongs to: Science Physics