The speed of light is maximum in MCQ with Answer and Explanation

The speed of light is maximum in
A. Water
B. Diamond
C. Glass
D. Vacuum
Answer: Option D
Solution (By JKSSB Mock Tests)
Light speed max in vacuum c = 3×10⁸ m/s. Slower in medium, v = c/n. Higher n, slower. Diamond n≈2.42, speed lowest. Vacuum n=1.

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Practice More Physics Questions

Question #1
A 60 W bulb operates at 120 V. Its resistance is
A. 60 Ω
B. 120 Ω
C. 480 Ω
D. 240 Ω

Correct Answer: Option D


Explanation:
R = V²/P = 14400/60 = 240 Ω.

This question belongs to: Science Physics
Question #2
Ohm's law is valid for
A. Electrolytes
B. Semiconductors only
C. Metallic conductors at constant temperature
D. All conductors

Correct Answer: Option C


Explanation:
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.

This question belongs to: Science Physics
Question #3
The time period of revolution of a satellite close to Earth's surface is approximately:
A. 90 minutes
B. 24 hours
C. 12 hours
D. 84 minutes

Correct Answer: Option D


Explanation:
For low Earth orbit (r ≈ R_earth), orbital period T = 2π√(r³/GM). Using g = GM/R², T = 2π√(R/g). With R = 6.4×10⁶ m, g = 9.8 m/s², T ≈ 2×3.14×√(6.4e6/9.8) ≈ 6.28×√(653061) ≈ 6.28×808 ≈ 5076 s ≈ 84.6 minutes. Memory aid: 'Low orbit period ≈ 84 min; geostationary = 24 hours'. This standard result is frequently tested in competitive exams. Always recall that period increases with orbital radius; competitive exams often compare low orbit vs geostationary periods.

This question belongs to: Science Physics