Spherical Mirror

Spherical mirror, a piece cut out of a reflective sphere, has one of its side opaque and the other side highly polished. Depending upon the nature of the reflecting surface of the mirror, the spherical mirror is classified as convex and concave mirror. When the reflective surface of a curved mirror bulges toward the light source, it is called convex or diverging mirror whereas when a reflecting surface of a curved mirror bulges inward (away from the incident light), it is called concave or converging mirror. Convex mirrors are not used to focus light as they reflect light outwards. They always form a virtual image, since the focus (F), a point in which the rays of light meet after being reflected or refracted, and the centre of curvature (C), the centre of the hollow sphere from which the mirror has been cut , are both imaginary points , which cannot be taken on screen. However, Concave mirrors are used to focus light as they reflect light inward to one focal point. They show different image types depending on the distance between the object and the mirror.

Aim:

To observe the position and characteristics of images produced by curved mirrors.

Hypothesis:

All images produced by the convex mirror will be virtual, upright and less magnified; however, the image produced by concave mirror will vary according to the position of the object.

Equipment:

Mirrors (concave and convex)

Meter ruler

Screen

Holding blocks

Plain white paper

Candle

Method:

Focal length of concave mirrors.

Arrange your mirror, meter ruler, and screen as shown in figure 3. Point the mirror at a distant object 9 greater than 10 m) and move the screen along the meter ruler until you obtain a sharp image of the object on the screen. The distance between the mirror and the screen is the approximate focal length of the mirror.

Real Images produced by concave mirrors

You now know the focal length of the mirror. The centre of curvature is double the focal length. Arrange the two meter rulers, mirror, candle, and screen. Darken the room.

Place the candle at a distance greater than C from the mirror. Move the screen back and forth along the ruler until you obtain a sharp image of the candle. Determine the position of the image in relation to the mirror.

Place the candle at C. Locate the image by moving the screen.

Place the candle at a position that is between F and C. Move the screen back and forth to locate the image. Measure the distance of the image from the mirror.

Virtual Images Produced by Concave Mirrors

Move the candle until it is between F and A. See if you can locate an image on the screen. Observe the image in the mirror.

Convex Mirrors

Place the convex mirror in the holder. Place the candle at some distance from it. Try to obtain an image on the screen. Move the mirror, or screen, or both, to several positions. Study the image in the mirror.

Results:

Part A

Focal point=25cm

Part B