The slope of a velocity-time graph gives MCQ with Answer and Explanation

Explanation:
λ = v/f = 350/500 = 0.7 m.

Explanation:
Fringe width β = λD/d, where λ wavelength, D screen distance, d slit separation. New d' = 2d, new D' = D/2. Thus β' = λ(D/2)/(2d) = λD/(4d) = β/4. Fringe width reduces to one-fourth. Memory tip: 'β ∝ D/d; changes multiply'. This proportional reasoning problem tests wave optics understanding, frequently appearing in competitive exams. Always track how each parameter change affects the result; combine multiplicative factors for net effect. Verify with dimensional analysis: β has length dimension, consistent with λD/d.

Explanation:
Dispersion: separation due to different refractive indices for different colours. Refraction is bending. Scattering (Tyndall effect) makes sky blue. Total internal reflection in optical fibers.