GSEB Solutions for Class 7 Science and Technology – Curved Mirrors (English Medium)
A curved mirror has a smooth and polished surface, though the curvature could be irregular. The non-uniform magnification of the different parts of our body causes distortion. Hence, our image appears long or short, inverted or erect, thick or thin in a curved mirror.
When you hold the inner side of a spoon in front of your face, the image seen appears to be larger when compared to the image seen on the outer side of the spoon which the face appears smaller.
Your face would appear long and thin in the outer shining surface of a steel glass.
A concave mirror can be prepared this way.
- Take a watch glass and shinning paper.
- Paste the shinning paper on the outer surface of the watch glass with an adhesive.
- Paint the inner surface of the watch glass. The convex mirror is now ready to use.
Yes, we get a point size image of the rays reflected from a concave mirror.
Radius of curvature of a curved mirror can be found using the following method:
R = 2f
R = 2 × 6 cm
R = 12 cm
Position of the candle: Beyond the centre of curvature (C)
Position of the image: Between the centre of curvature (C) and the focal length (F)
Type of image is observed: Inverted.
Size of the image: Smaller than the flame of the candle
- Concave mirrors are used as reflectors in torches.
- A concave mirror is used as a reflector in the headlights of vehicles and also as the lens of a compound microscope.
- Dentists use concave mirrors to see enlarged images of the teeth.
- Concave mirrors are used by the ENT (Ear, Nose and Throat) specialists to focus light in nose, ears and throat.
- Parabolic mirrors are used to cook food in parabolic solar cookers.
- Convex mirrors are used in vehicles as rear view mirrors to see other vehicles coming from behind.
- Convex are used as reflectors in streetlights to spread light over a greater area.
- Convex mirrors are used in big hotels and shopping malls for security purposes.
The vessel is kept at the point where the reflected sunrays are concentrated and becomes hot.
Position of the candle: In front of the mirror at some distance.
Position of the image: The image is formed behind the mirror.
Size of the image: The image formed is smaller than the size of the candle.
Type of image: The image formed cannot be obtained on a screen and is virtual in nature.
- Convex mirrors always produce a smaller, virtual, and erect image of an object. Hence, they are used as side view mirrors in vehicles. They form images of the vehicles which are spread over a relatively larger area providing a wider field view.
- Convex mirrors are also used for security reasons in shops, malls, etc.
This because the mirror used is a convex mirror which forms an erect and small image of the object. It provides a wider fied of view allowing the drivers to see more area. Thus, the driver can clearly see the movement of vehicles coming from behind in the convex mirror used as a rear-view mirror and can drive the vehicle safely.
The image formed by a convex mirror is virtual in nature and appears behind the mirror. This helps a receptionist to observe the people in the reception area from the mirror. Thus, the receptionist can make a note of any suspicious people around.
A searchlight is used to project a powerful beam of light in a particular direction. The rays emerging from of an object placed at the principal focus of a concave mirror get reflected by it and travel parallel to the principal axis for a long distance. Hence, a concave mirror is used in searchlights
When an object is placed far away from a convex mirror, a virtual, erect and highly diminished image is obtained.