A ray of light passes from air to glass. Which quantity remains unchanged?
A. Wavelength
B. Frequency
C. Speed
D. Amplitude
Answer: Option B
Solution (By JKExamLibrary)
When light crosses media, frequency remains constant as it's determined by the source. Speed and wavelength change proportionally: v = fλ, and v = c/n, so λ decreases in denser medium (glass). Amplitude may change due to reflection/transmission coefficients. Memory aid: 'Frequency is source-dependent; speed and wavelength are medium-dependent'. This fundamental wave property is frequently tested in refraction questions. Competitive exams often use this to assess understanding of wave behavior at interfaces. Always recall that color (frequency) doesn't change during refraction, though speed and wavelength do.
Explanation:
For perpendicular forces: R = √(F₁² + F₂²) = √(9 + 16) = √25 = 5 N. Pythagorean theorem applies for vector addition at 90°. Memory aid: '3-4-5 triangle for perpendicular forces'. Basic vector addition problem testing magnitude calculation, common in mechanics sections of competitive exams.
Explanation:
The principle of homogeneity states that you can only add or subtract physical quantities that have the exact same dimensional formula (you can't add mass to length). Therefore, in the equation A = B + C, the terms B and C must have the same dimensions, and their sum will yield a quantity A that also shares those exact same dimensions.
No comments yet. Be the first to start the discussion!