JEE Physics - MCQ Practice Questions

For total internal reflection from denser to rarer medium, sin(θc) = n₂/n₁ where n₁ is refractive index of denser medium and n₂ of rarer medium

Using mirror formula: 1/f = 1/u + 1/v. $\frac{1}{10}$ = $\frac{1}{15}$ + 1/v. v = 30 cm. Magnification m = -v/u = -$\frac{30}{15}$ = -2

Power combination: P = P₁ + P₂ = 5 + (-2) = 3 D. Focal length f = 1/P = $\frac{1}{3}$ = 0.33 m

n = c/v. 1.5 = (3 × 10⁸)/v. v = (3 × 10⁸)/1.5 = 2 × 10⁸ m/s

When mirror moves towards object at speed v, the image also moves towards object at speed v. Therefore, relative speed = v + v = 2v = 10 m/s

Wavelength in medium = λ_vacuum / n = $\frac{500}{1}$.5 = 333.3 nm. Frequency remains constant in different media.

For magnified real image in concave mirror, object distance u must be between f and 2f (between focus and center of curvature), giving magnification m > 1.

sin(critical angle) = 1/n. sin(45°) = 1/√2 = 1/n, therefore n = √2 ≈ 1.414

Violet has smaller λ, higher frequency, and the medium has higher n for violet (dispersion). All factors lead to greater deviation.

Negative power indicates concave lens (f = -20 cm). Concave lens is used to correct myopia (short-sightedness).

Resolving power = 1/(minimum resolvable distance) ∝ 1/λ. Shorter wavelength gives better resolution. UV microscopy uses shorter wavelengths.