a) State Huygen's principle. Does it apply to sound wave in air? b) Differentiate unpolarized and polarized light. GROUP: B Short answer questions 3x4=12

a) Huygen's Principle and Its Applicability to Sound Waves in Air Huygen's principle states that: "Every point on a wavefront acts as a source of secondary wavelets, and the new wavefront is the tangential surface to these secondary wavelets." This principle applies to all types of waves , including sound waves in air , because sound is a longitudinal wave that propagates through a medium (air) via particle vibrations. The principle explains phenomena like reflection, refraction, and diffraction of sound waves. b) Differentiation of Unpolarized and Polarized Light Feature Unpolarized Light Polarized Light Definition Light waves oscillate in all directions perpendicular to the direction of propagation. Light waves oscillate in a single plane (or a fixed direction). Source Produced by incandescent bulbs, sunlight, or flames . Produced by reflection (e.g., from water surfaces), scattering, or polarizing filters . Polarization Direction No fixed polarization direction. Has a specific polarization axis (e.g., vertical, horizontal, or at an angle). Intensity Variation Intensity remains constant in all directions. Intensity varies with orientation (e.g., blocked by a polarizing filter at 90°). Phenomena Does not show Malus' law effects. Follows Malus' law : I = I 0 ^2 . Example Sunlight before passing through a polarizer. Light after passing through a Polaroid sheet .

a) State Huygen's principle. Does it apply to sound wave in air? b) Differentiate… – Physics NEB 2076 (old course) Solution

ह्युगेन्सको सिद्धान्त र तरङ्ग प्रकाशिकीको विकासमा प्रमुख घटनाहरू।

a) Huygen's Principle and Its Applicability to Sound Waves in Air

Huygen's principle states that:

"Every point on a wavefront acts as a source of secondary wavelets, and the new wavefront is the tangential surface to these secondary wavelets."

This principle applies to all types of waves, including sound waves in air, because sound is a longitudinal wave that propagates through a medium (air) via particle vibrations. The principle explains phenomena like reflection, refraction, and diffraction of sound waves.

b) Differentiation of Unpolarized and Polarized Light

Feature	Unpolarized Light	Polarized Light
Definition	Light waves oscillate in all directions perpendicular to the direction of propagation.	Light waves oscillate in a single plane (or a fixed direction).
Source	Produced by incandescent bulbs, sunlight, or flames.	Produced by reflection (e.g., from water surfaces), scattering, or polarizing filters.
Polarization Direction	No fixed polarization direction.	Has a specific polarization axis (e.g., vertical, horizontal, or at an angle).
Intensity Variation	Intensity remains constant in all directions.	Intensity varies with orientation (e.g., blocked by a polarizing filter at 90°).
Phenomena	Does not show Malus' law effects.	Follows Malus' law: $I = I_{0} cos^{2} θ$ .
Example	Sunlight before passing through a polarizer.	Light after passing through a Polaroid sheet.

a) State Huygen's principle. Does it apply to sound wave in air? b) Differentiate unpolarized and polarized light. GROUP: B Short answer questions 3x4=12

a) Huygen's Principle and Its Applicability to Sound Waves in Air

b) Differentiation of Unpolarized and Polarized Light

Discussion

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