Science Class X - Light and Reflection

Vocabulary terms and definitions related to the physics of light, reflection laws, and spherical mirror characteristics based on the Class X Science lecture.

Light

A form of energy that helps us see objects by reflecting off them and entering our eyes.

Reflection of Light

The phenomenon in which light bounces back into the same medium after striking a smooth or polished surface.

Incident Ray

The ray of light that falls on the reflecting surface.

Reflected Ray

The ray of light that bounces back after striking a reflecting surface.

Normal

A perpendicular line drawn at the point where the incident ray strikes the surface.

Angle of Incidence

The angle between the incident ray and the normal, represented as $\angle i$.

Angle of Reflection

The angle between the reflected ray and the normal, represented as $\angle r$.

Laws of Reflection

(i) The angle of incidence ($\angle i$) is equal to the angle of reflection ($\angle r$); (ii) The incident ray, the reflected ray, and the normal at the point of incidence all lie in the same plane.

Plane Mirror

A smooth and polished surface that reflects light uniformly, creating a virtual, erect, and laterally inverted image of the same size as the object.

Lateral Inversion

A phenomenon where the left side of an object appears as the right side and the right side appears as the left side in a mirror.

Spherical Mirror

A mirror whose reflecting surface forms part of a hollow sphere, which can be curved either inwards or outwards.

Concave Mirror

A spherical mirror with its reflecting surface curved inward, facing towards the centre of the sphere; also known as a converging mirror.

Convex Mirror

A spherical mirror with its reflecting surface curved outward; also known as a diverging mirror.

Pole ($P$)

The central point of the reflecting surface of a spherical mirror.

Centre of Curvature ($C$)

The center of the imaginary sphere of which the mirror's reflecting surface forms a part.

Radius of Curvature ($R$)

The radius of the sphere of which the mirror's reflecting surface forms a part, calculated as $R = 2f$.

Principal Axis

The straight line passing through the pole ($P$) and the centre of curvature ($C$) of a mirror.

Principal Focus ($F$)

The point on the principal axis where parallel rays of light either converge or appear to diverge after reflection.

Focal Length ($f$)

The distance between the pole ($P$) and the principal focus ($F$) of a spherical mirror, where $f = \frac{R}{2}$.

Aperture

The diameter of the reflecting surface of the spherical mirror.