There are some mirrors that distort the reflected image. Cosmetic mirrors magnify things, and other mirrors make things look smaller.

Curved Mirrors

A curved mirror is a section of a sphere. If the outside surface of the sphere is reflecting, the mirror is convex. If the inside surface is reflecting, the mirror is concave.

The characteristics (SALT) of the image formed can be: larger, smaller or the same size of the object inverted or upright in front or behind the mirror real or virtual

Parts of the concave mirror: Vertex (V) – the centre of the mirror Principal Axis (PA) — line that goes through V Focus (F)—where the reflected rays of parallel incident rays intersect Centre of Curvature (C)—the centre of the sphere from which the mirror was cut

By drawing ray diagrams, you can find out how the image would be. Draw a ray parallel to the principal axis from the top of object to the curved mirror. After reflecting off mirror, the ray passes through the focal point.

Draw a ray from the top of the object through the focal point. The ray will be parallel to the optical axis after reflecting.

Draw a ray aimed at the vertex from the top of object to the curved mirror. After reflecting off mirror, the ray’s passes at the same angle below the principal axis.

Draw a ray aimed at the centre of curvature from the top of object to the curved mirror. After reflecting off mirror, the ray reflects back on itself.

Use any two rules to determine the characteristics of the image. Draw the image as a vertical arrow with its tail on the principle axis and the head at the point where the two reflected rays meet.

The characteristics (SALT) of the image formed are: smaller inverted in front of the mirror real

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Practice your ray diagrams on the following. Draw the image. State the characteristics of each image.

Answers

Convex Mirrors

Parts of the convex mirror: Vertex (V) – the centre of the mirror Principal Axis (PA) — line that goes through V Focus (F)—where the reflected rays of parallel incident rays intersect Centre of Curvature (C)—the centre of the sphere from which the mirror was cut

By drawing ray diagrams, you can find out how the image would be. Draw ray parallel to principal axis. After reflection, this ray travels as if it is coming from the focus.

Draw line from top of object to centre, C. After reflection, this ray travels back on itself as if it is coming from the centre of curvature.

Draw line from top of object to the focus, F. After reflection, this ray travels back parallel to the principal axis.

Use any two rules to determine the characteristics of the image. The virtual image is drawn using a dotted line with an arrow. Tip: Images formed by a convex mirror are always smaller, upright, and virtual.

Practice: Practice your ray diagrams on the following. Draw the image. State the characteristics of each image.