Reflection of Light from Spherical Mirrors Chapter 3 Reflection of Light from Spherical Mirrors

Concave and Convex Mirrors The reflecting surface of a concave mirror “caves in” at the centre. The reflecting surface of a convex mirror bulges out at the centre.

Describing Concave and Convex Mirrors

A ray strikes the pole of a concave mirror. What is its path after reflection at the mirror? It is reflected at an equal angle with the axis.

A ray which passes through the centre of curvature strikes a concave mirror. What is its path after reflection at the mirror? It is reflected back along its own path.

A ray which comes in parallel to the axis strikes a concave mirror. What is its path after reflection at the mirror? It passes through the focus after reflection.

A ray passes through the focus and then strikes a concave mirror. What is its path after reflection at the mirror? It is reflected out parallel to the axis.

What is a Real Image? A Real Image is an image formed by the actual intersection of rays. A real image can be formed on a screen.

Real Image in a Concave Mirror After reflection at the mirror each of the rays from P passes through the same point X. A Real Image of P is formed at X.

A Real Image is formed in a Concave Mirror if the object is outside the focus. A Real Image in a Concave Mirror is always: Inverted. In front of the mirror.

Real Image in a Concave Mirror

What is a Virtual Image? A Virtual Image is an image formed by the Apparent Intersection of Rays. A virtual image cannot be formed on a screen.

A Virtual Image is formed in a Concave Mirror if the object is inside (or on) the focus. A Virtual Image in a Concave Mirror is always: Upright (erect). Magnified. Behind the mirror.

Virtual Image in a Concave Mirror

Uses of a concave mirror A dentist’s mirror. Floodlights. A projector. A torch. A cosmetics/shaving mirror. A solar furnace. A solar furnace used as a barbecue.

A Magnified Upright Virtual Image

A Concave Mirror being used in a floodlight A Concave Mirror being used in a floodlight. The bulb is at or near the focus.

Formulae for a Concave Mirror u is the distance from the object to the mirror. v is the distance from the image to the mirror. f is the focal length and m is the magnification If the image is real: If the image is virtual:

Convex Mirrors

A ray strikes the pole of a convex mirror. What is its path after reflection at the mirror? It is reflected at an equal angle with the axis.

A ray which is heading for the centre of curvature strikes a convex mirror. What is its path after reflection at the mirror? It is reflected back along its own path.

A ray which comes in parallel to the axis strikes a convex mirror. What is its path after reflection at the mirror? It is reflected as if it came from the focus.

A ray which is heading for the focus strikes a convex mirror. What is its path after reflection at the mirror? It is reflected out parallel to the axis.

Image formation in a Convex Mirror After reflection at the mirror each of the rays from P appears to pass through the same point X. A Virtual Image of P is formed at X.

The Image in a Convex Mirror is always: Virtual Diminished Upright (erect) Behind the mirror

u is the distance from the v is the distance from the Formulae for a Convex Mirror u is the distance from the object to the mirror. v is the distance from the image to the mirror. f is the focal length m is the magnification

A Convex Mirror gives a larger field of view than a Plane Mirror.

A convex mirror is used in a supermarket

A driving mirror is usually Convex

To measure the Focal Length ( f ) of a Concave Mirror