The colour of an object is due to MCQ with Answer and Explanation

The colour of an object is due to
A. Transmission of that colour
B. Absorption of all colours
C. Reflection of that colour
D. Emission of that colour
Answer: Option C
Solution (By JKExamLibrary)
Object reflects that colour and absorbs others.

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Practice More Physics Questions

Question #1
The kinetic energy of a body is increased by 300%. The percentage increase in its momentum is:
A. 100%
B. 300%
C. 400%
D. 200%

Correct Answer: Option A


Explanation:
KE ∝ p² (since KE = p²/(2m)). If KE increases by 300%, new KE = 4× original KE. Thus p_new² / p_original² = 4 ⇒ p_new / p_original = 2 ⇒ momentum doubles, i.e., 100% increase. Memory tip: 'KE ∝ p²; so %Δp = ½ %ΔKE for small changes, but for large changes use ratio'. This proportional reasoning problem tests energy-momentum relationship, frequently appearing in competitive exams. Always derive from fundamental relations when percentages are large; linear approximations fail here.

This question belongs to: Science Physics
Question #2
One astronomical unit (AU) is the
A. Distance between Earth and Moon
B. Distance travelled by light in one year
C. Distance between Earth and Sun
D. Radius of Earth

Correct Answer: Option C


Explanation:
1 AU ≈ 1.5 × 10⁸ km, average Earth-Sun distance.

This question belongs to: Science Physics
Question #3
A 60 W bulb is used for 5 hours daily. How much electrical energy is consumed by the bulb in 30 days?
A. 9 kWh
B. 90 kWh
C. 0.9 kWh
D. 900 kWh

Correct Answer: Option A


Explanation:
Electrical energy (E) = Power (P) × Time (t). Power = 60 W = 0.06 kW. Time per day = 5 hours. Total time in 30 days = 5 × 30 = 150 hours. Energy = 0.06 kW × 150 h = 9 kWh (or 9 units of electricity). One kWh is the commercial unit of energy.

This question belongs to: Science Physics