Explain the applications of rectilinear propagation of light

Explain the applications of rectilinear propagation of light.

Answers

1. Pinhole camera
It consists of a closed box with a small hole on one face and a screen of tracing paper/ frosted glass on the opposite face as shown. An image will be formed on the screen. Since light travels from one point of the object through the hole an image will be formed on the opposite screen of the box. If the object is near the hole it is magnified while diminished if away from the hole. Magnification is therefore the ration of the image to object height, expressed as, Magnification = height of image/ height of object or
= distance of image from pinhole/ distance of object from pinhole

2. Shadows
Shadows are formed when an opaque object is placed between a source of light and a screen. When the shadow is big a dark patch at the centre is formed (umbra) while a surrounding lighter patch called penumbra is formed.

3. Eclipses
(i)Eclipse of the sun (solar eclipse)
This occurs when the moon is between the earth and the earth. The shadow of the moon falls on the earth’s surface. Sometimes the distance is large for the shadow to reach the earth and when this happens an annular eclipse occurs.

(ii)Eclipse of the moon
It is also known as lunar eclipse and occurs when the earth is between the sun and the moon. The shadow of the earth falls on the moon.

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raphael answered the question on October 11, 2018 at 06:07

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