Answer in Detail
1. Differentiate between opaque, translucent and transparent objects. Give tu.
2. How will you make a pinhole camera? Explain its working.
3. With the help of an activity, show that light travels in a straight line.
4. With the help of an experiment, show that both an opaque object and a sou
to form a shadow.
Give four characteristics of a shadow.
How do the length and the shape of the shadow change with the nosit
Answers
1. Transparent objects allow all the light to pass through them, translucent ones allow partial light to pass, whereas opaque ones allow no light to pass through.
2. Cut a square hole. Cut a square hole into the middle of one of your pieces of card stock.
Tape foil over the hole. Tape a piece of aluminum foil over the hole.
Poke a hole in the foil. Use your pin or paper clip to poke a small hole in the aluminum foil.
pinhole camera working
A pinhole camera is a simple camera without a lens but with a tiny aperture (the so-called pinhole) – effectively a light-proof box with a small hole in one side. Light from a scene passes through the aperture and projects an inverted image on the opposite side of the box, which is known as the camera obscura effect.
Two experiments are used to demonstrate how light travels in straight lines. In the first example, the presenter arranges three pieces of card, with holes in, in an uneven line. The light stops and cannot travel through all three cards. When she arranges the holes in a straight line, the light can travel through.
Explanation:
1- Transparent Object: An object which allows complete passage to light is called a transparent object. We can clearly see through a transparent object.
Translucent Object: An object which allows partial passage to light is called a translucent object. We can see through a translucent object but the vision would be faint.
Opaque Object: An object which does not allows passage to light is called an opaque object. We cannot see through an opaque object
2-A pinhole camera is composed of two boxes. One of the boxes snugly fits inside another box and can be slid to and fro. There is a pin-sized hole at the front of the camera and a translucent screen at the back of the camera. The distance between the pin-hole and screen can be adjusted to obtain a clear image of an object.
3 two experiments are used to demonstrate how light travels in straight lines. In the first example, the presenter arranges three pieces of card, with holes in, in an uneven line. The light stops and cannot travel through all three cards. When she arranges the holes in a straight line, the light can travel through.
4- When light falls on an opaque object, a dark patch is formed on the other side of the object; if a screen is present on the other side. Three things are required for formation of shadow, viz. a source of light, an object and a screen
5- he size of shadow depends on the distance of source of light and on the angle at which the light rays fall on the object.
If the source of light is closer to the object, a larger shadow is formed than when the source of light is far from the object.
If the angle of incident light is smaller, the shadow is longer. On the other hand, if the angle of incident light is bigger, the shadow is smaller. This explains, why our shadows are longer in the morning and evening and smaller in the noon.