ICSE Class 6 Answered

Give an experiment to demonstrate that light travels in a straight line.

Asked by Topperlearning User | 14 May, 2015, 03:10: PM

Expert Answer

Experiment:

Take three cardboard squares of equal size. Locate the centre of each pieces of cardboard by drawing the diagonals.
With the help of a nail, make a hole at the centre of each cardboard. Now fix the three card boards on plasticine or on stands so that they remain upright.
Arrange the three card boards A, B and C, one behind the other such that their centres are in the same horizontal line. You can pass a knitting needle through the holes to confirm if they are in a straight line.
Now place a burning candle in front of the board C and look through the pinhole in board A. The flame will be clearly visible. This shows that light travels in a straight line. Now, move board B slightly and again look through the pinhole in board A as shown in the figure.
You will not be able to see the flame. This shows that light does not travel in a zig-zag way.

By this experiment, we can conclude that light travels in a straight line. This property of light is called rectilinear propagation of light.

Answered by | 14 May, 2015, 05:10: PM

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