Revision: Wonders of Light 2 Science and Technology 1 SSC (English Medium) 10th Standard Maharashtra State Board

A normal is an imaginary line drawn perpendicular to the boundary at the point of incidence.

When travelling obliquely from one medium to another, the direction of propagation of light in the second medium changes. This phenomenon is known as refraction of light.

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Light changes its direction when going from one transparent medium to another transparent medium. This is called the refraction of light.

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The bending of the light ray from its path in passing from one medium to the other medium is called 'refraction' of light.

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When a ray of light impinges on a polished, smooth, shiny surface, the rebounding of light within the same medium is called reflection of light.

The change in the direction of the path of light when it passes from one transparent medium to another transparent medium is called refraction. The refraction of light is essentially a surface phenomenon.

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When light passes from one transparent medium to another, its speed and direction change. This is called refraction.

The ray that enters the second medium after crossing the boundary is called the refracted ray.

Light rays that are parallel to the principal axis of a concave mirror converge at a specific point on its principal axis after reflecting from the mirror. This point is known as the principal focus of the concave mirror.

1. Incident ray: The ray of light which falls on the mirror surface is called the incident ray.
2. Point of incidence: The point at which the incident ray falls on the mirror is called the point of incidence.
3. Normal: The normal is a line at right angles to the mirror surface at the point of incidence.
4. Reflected ray: The ray of light which is sent back by the mirror is called the reflected ray.
5. Angle of incidence: The angle of incidence is the angle made by the incident ray with the normal at the point of incidence.
6. Angle of reflection: The angle of reflection is the angle made by the reflected ray with the normal at the point of incidence.

Refracted light is the part of light enters into the other medium and travels in a straight path but in a direction different from its initial direction and is called the refracted light.

It is defined as the ratio of the velocity of light in medium 1 to the velocity of light in medium 2.

The perpendicular distance XY between the path of the emergent ray BC and the direction of the incident ray OD is called the lateral displacement.

The perpendicular distance XY between the path of the emergent ray BC and the direction of the incident ray OD is called the lateral displacement.

It is defined as the ratio of the velocity of light in medium 1 to the velocity of light in medium 2.

The optical illusion of water or distant objects caused by refraction of light due to temperature differences in air layers is called a mirage.

An arc of seven colours with red on the inner edge and violet on the outer edge, caused by double total internal reflection inside water droplets, is called a secondary rainbow.

An arc of seven colours formed in the sky with red on the outer edge and violet on the inner edge, caused by single total internal reflection inside water droplets, is called a primary rainbow.

The laws of refraction are fundamental for board examinations and objective tests.

First law

The incident ray, the refracted ray, and the normal at the point of incidence all lie in the same plane.

Second law

For a given pair of media, the ratio of the sine of the angle of incidence to the sine of the angle of refraction remains constant.

\[\frac {\text {sin i}}{\text {sin r}}\] = constant

This constant is called the refractive index of the second medium with respect to the first medium.

Ray 2 shows partially reflected ray.

1. First Law: Incident ray, refracted ray, and normal to the interface at the point of incidence all lie in the same plane.

2. Second Law (Snell's Law): \[\frac{\sin i}{\sin r}=\mathrm{constant}=\frac{\mu_2}{\mu_1}\]

Extended Snell's Law: \[\frac{\sin i}{\sin r}=\frac{\mu_2}{\mu_1}=_1\mu_2=\frac{v_1}{v_2}=\frac{\lambda_1}{\lambda_2}\]

Ray 2 shows partially reflected ray.