#wavefront

Optical Phenomena and Applications

What is the shape of the wavefront reflected by a plane mirror when a spherical wave is incident on it?

**Convex lens focusing** plane wave into point because lens introduces phase delay proportional to thickness, converting plane wavefront to spherical converging to focal point, property ensures rays parallel to axis meet at focus, spherical aberration minimized for paraxial rays, lensmaker's formula determines focal length. A spherical wavefront incident on a plane mirror reflects as a spherical wavefront, diverging from the mirror’s virtual focus. Using Δ = d sinθ, y = n λ D/d, a sinθ = n λ, I = I₀ cos²θ, n = c/v, sinC = 1/n, λ' = λ/n and A = 2a cos(φ/2), calculation gives Spherical, illustra

Ref: NCERT > Physics Book > Wave Optics > Optical Phenomena and Applications

View Details

Optical Phenomena and Applications

What is the nature of the wavefront produced by a plane wave after reflection from a concave mirror?

**Polarization requires transverse waves** because only transverse can have orientation perpendicular to propagation, longitudinal cannot be polarized, wave theory requires light transverse to explain polarization, polaroids transmit only component along pass-axis, unpolarized has random transverse orientations, after polaroid polarized. A plane wave reflecting off a concave mirror forms a spherical wavefront converging to the focal point. Using Δ = d sinθ, y = n λ D/d, a sinθ = n λ, I = I₀ cos²θ, n = c/v, sinC = 1/n, λ' = λ/n and A = 2a cos(φ/2), calculation gives Spherical, illustrating inte

Ref: NCERT > Physics Book > Wave Optics > Optical Phenomena and Applications

View Details

Optical Phenomena and Applications

What is the shape of the refracted wavefront when a plane wave passes through a convex lens and converges to a point?

**Incoherent sources** intensity adds I = I₁+I₂, no interference pattern because phase random, two independent sources cannot produce stable interference because phase difference fluctuates rapidly, coherent sources required with constant phase, laser coherent, visibility of fringes requires coherence, degree of coherence determines contrast. A plane wave passing through a convex lens forms a spherical wavefront converging to the focal point. Using Δ = d sinθ, y = n λ D/d, a sinθ = n λ, I = I₀ cos²θ, n = c/v, sinC = 1/n, λ' = λ/n and A = 2a cos(φ/2), calculation gives Spherical, illustrating i

Ref: NCERT > Physics Book > Wave Optics > Optical Phenomena and Applications

View Details

Wave Properties, Frequency and Energy Conservation

What is the shape of the wavefront after a plane wave passes through a thin prism?

**Intensity not depend on speed** when enters denser medium because intensity I ∝ n E₀²? Actually Poynting vector S = E×H, energy density u =½ ε E², for same amplitude E₀ intensity proportional to n, but amplitude changes at interface due to reflection, total energy conserved incident = reflected + transmitted, interference does not destroy energy, it redistributes. A plane wave passing through a prism gets tilted due to the varying thickness, resulting in a tilted plane wavefront. Using Δ = d sinθ, y = n λ D/d, a sinθ = n λ, I = I₀ cos²θ, n = c/v, sinC = 1/n, λ' =

Ref: NCERT > Physics Book > Wave Optics > Wave Properties, Frequency and Energy Conservation

View Details

Polarization and Malus Law

What is the direction of energy propagation relative to the wavefront in a light wave?

**Two polaroids** with pass-axes perpendicular intensity zero because second blocks component, with 45° intensity I₀/4 if initial after first I₀, if initial unpolarized I₀, after first I₀/2 then after second at 45° I₀/4. Three polaroids first and third crossed 90°, middle at 45° maximum transmission because middle rotates polarization, I after first I₀/2, after middle at 45° I₀/4, after third at 45° to middle I₀/4×cos²45°= I₀/8, non-zero, maximum when middle 45°. The energy of a wave travels perpendicular to the wavefront. Using Δ = d sinθ, y = n λ D/d, a sinθ = n λ, I = I₀ cos²θ, n = c/v, sin

Ref: NCERT > Physics Book > Wave Optics > Polarization and Malus Law

View Details

Wavefront and Huygens Principle

What is the shape of the wavefront from a distant star intercepted by Earth?

**Wavefront types** point source spherical, distant point source plane, after convex lens plane wave focuses to point because lens adds phase delay proportional to thickness, converging spherical wavefront, after concave mirror plane wave becomes spherical converging to focus, illustrating Huygens construction. At a large distance from a point source like a star, a small portion of the spherical wavefront appears plane. Using Δ = d sinθ, y = n λ D/d, a sinθ = n λ, I = I₀ cos²θ, n = c/v, sinC = 1/n, λ' = λ/n and A = 2a cos(φ/2), calculation gives Plane, illustrating interference, diffraction an

Ref: NCERT > Physics Book > Wave Optics > Wavefront and Huygens Principle

View Details

Wavefront and Huygens Principle

Why does the reflected wavefront from a plane surface maintain the same angle as the incident wavefront?

**Wavefront** is locus of points in same phase, spherical from point source, plane at large distance because radius large, Huygens principle every point on wavefront acts as secondary source of wavelets, new wavefront envelope of secondary wavelets, allows prediction of new wavefront shape from known wavefront, explains reflection and refraction. The wave model shows that secondary wavelets from the surface form a reflected wavefront where the angle of incidence equals the angle of reflection due to geometric symmetry. Using Δ = d sinθ, y = n λ D/d, a sinθ = n λ, I = I₀ cos²θ, n = c/v, sinC =

Ref: NCERT > Physics Book > Wave Optics > Wavefront and Huygens Principle

View Details

Wavefront and Huygens Principle

What is the shape of the wavefront produced by a point source in a uniform medium?

**Wavefront types** point source spherical, distant point source plane, after convex lens plane wave focuses to point because lens adds phase delay proportional to thickness, converging spherical wavefront, after concave mirror plane wave becomes spherical converging to focus, illustrating Huygens construction. A point source emits waves uniformly in all directions, producing spherical wavefronts in a medium where the speed is isotropic. Using Δ = d sinθ, y = n λ D/d, a sinθ = n λ, I = I₀ cos²θ, n = c/v, sinC = 1/n, λ' = λ/n and A = 2a cos(φ/2), calculation gives Spherical, illustrating interf

Ref: NCERT > Physics Book > Wave Optics > Wavefront and Huygens Principle

View Details

Wavefront and Huygens Principle

What is the shape of the wavefront after a plane wave passes through a thin prism?

**Wavefront** is locus of points in same phase, spherical from point source, plane at large distance because radius large, Huygens principle every point on wavefront acts as secondary source of wavelets, new wavefront envelope of secondary wavelets, allows prediction of new wavefront shape from known wavefront, explains reflection and refraction. A plane wave passing through a thin prism gets delayed variably, resulting in a tilted plane wavefront. Using Δ = d sinθ, y = n λ D/d, a sinθ = n λ, I = I₀ cos²θ, n = c/v, sinC = 1/n, λ' = λ/n and A = 2a cos(φ/2), calculation gives Tilted plane, illus

Ref: NCERT > Physics Book > Wave Optics > Wavefront and Huygens Principle

View Details

Wavefront and Huygens Principle

What is the shape of the wavefront emitted by a point source in a uniform medium close to the source?

**Huygens principle** predicts shape of wavefront after propagation, for point source close spherical, far plane, after reflection from plane mirror spherical wave becomes spherical with centre mirrored, plane wave remains plane but direction changes angle of incidence equals reflection, after passing through thin prism plane wavefront tilts due to different path. A point source in a uniform medium emits spherical wavefronts, especially close to the source. Using Δ = d sinθ, y = n λ D/d, a sinθ = n λ, I = I₀ cos²θ, n = c/v, sinC = 1/n, λ' = λ/n and A = 2a cos(φ/2), calculation gives Spherical,

Ref: NCERT > Physics Book > Wave Optics > Wavefront and Huygens Principle

View Details

Wavefront and Huygens Principle

What is the direction of rays relative to the wavefront in a light wave?

**Huygens principle** predicts shape of wavefront after propagation, for point source close spherical, far plane, after reflection from plane mirror spherical wave becomes spherical with centre mirrored, plane wave remains plane but direction changes angle of incidence equals reflection, after passing through thin prism plane wavefront tilts due to different path. Rays are perpendicular to the wavefront, representing the direction of energy propagation. Using Δ = d sinθ, y = n λ D/d, a sinθ = n λ, I = I₀ cos²θ, n = c/v, sinC = 1/n, λ' = λ/n and A = 2a cos(φ/2), calculation gives Perpendicular,

Ref: NCERT > Physics Book > Wave Optics > Wavefront and Huygens Principle

View Details

Wavefront and Huygens Principle

What is the shape of the wavefront emitted by a point source at a large distance?

**Wavefront** is locus of points in same phase, spherical from point source, plane at large distance because radius large, Huygens principle every point on wavefront acts as secondary source of wavelets, new wavefront envelope of secondary wavelets, allows prediction of new wavefront shape from known wavefront, explains reflection and refraction. At a large distance from a point source, the spherical wavefront appears plane over a small region. Using Δ = d sinθ, y = n λ D/d, a sinθ = n λ, I = I₀ cos²θ, n = c/v, sinC = 1/n, λ' = λ/n and A = 2a cos(φ/2), calculation gives Plane, illustrating int

Ref: NCERT > Physics Book > Wave Optics > Wavefront and Huygens Principle

View Details