Which of the following colours has the longest wavelength? MCQ with Answer and Explanation

Which of the following colours has the longest wavelength?
A. Green
B. Red
C. Violet
D. Blue
Answer: Option B
Solution (By JKExamLibrary)
Visible spectrum: red ~700 nm, orange, yellow, green, blue, indigo, violet ~400 nm. Red has longest wavelength, lowest frequency. Violet shortest wavelength, highest frequency. Remember VIBGYOR.

This question belongs to: Science Physics

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Practice More Physics Questions

Question #1 Report Error
Latent heat of fusion ice = 336 kJ/kg. Heat to melt 3 kg ice at 0°C:
A. 672 kJ
B. 112 kJ
C. 1008 kJ
D. 336 kJ

Correct Answer: Option C


Explanation:
Q = mL = 3×336 = 1008 kJ. Direct latent heat formula application. Memory tip: 'Phase change: Q = mL; no temperature change'. Calorimetry calculation frequently tested in competitive exams.

This question belongs to: Science Physics
Question #2 Report Error
1 nanometer equals
A. 10⁻⁹ m
B. 10⁻¹⁰ m
C. 10⁻¹² m
D. 10⁻⁶ m

Correct Answer: Option A


Explanation:
nano = 10⁻⁹. So 1 nm = 10⁻⁹ m. Angstrom = 10⁻¹⁰ m. picometer = 10⁻¹² m.

This question belongs to: Science Physics
Question #3 Report Error
A body is thrown vertically upwards. At the highest point of its trajectory:
A. Velocity and acceleration are zero
B. Both velocity and acceleration are maximum
C. Velocity is zero but acceleration is g downward
D. Velocity is maximum and acceleration is zero

Correct Answer: Option C


Explanation:
At maximum height, vertical velocity becomes zero momentarily. However, acceleration due to gravity (g) acts downward throughout the motion, including at the peak. Thus acceleration is g ≈ 9.8 m/s² downward, not zero. Memory tip: 'Peak of projectile: v=0, a=g downward'. This conceptual question tests understanding of motion under gravity, frequently appearing in competitive exams. Always distinguish velocity (which changes) from acceleration (constant in free fall near Earth). Misconception that acceleration is zero at peak is a common trap.

This question belongs to: Science Physics