Question

Light travels in a _____ path.
(A) Rectilinear
(B) Zig-zag
(C) Circular
(D)Helical

Answer 1

Hint:For understanding the path of the light, we have to consider some real life situations and observe what happens when there is some obstacle interfering with the path of light. For instance, formation of shadows on the wall when there is an object in the path between the light source and the wall.

Complete step by step answer:
Let us understand this concept of the path of light travel by a simple example.

Here, we consider two cases.
In first case A, we put cardboard between the candle and the observer, as a result, the observer cannot see the light of the candle.In case B, a hole is created in the cardboard. Now, when the observer tries to see the candle, it will be clearly visible as shown in figure.
By this experiment we can say that light travels in a straight line. This process of light travelling along a straight line without any interference in its path is called the rectilinear propagation of light.Another example of rectilinear propagation of light is lunar eclipse in which the earth comes in the path of light coming from the sun to the moon. In this case, we can see the shadow of our planet earth on the moon. However, as soon as the earth gets out of the path of light, the shadow disappears and we can see the moon clearly.These two examples prove that the light possesses the property of rectilinear propagation and thus travels in a rectilinear path.

Hence, option A is the right choice.

Note:Here, we have seen that the light travels in a rectilinear path. This path may change if there is a change in the medium in which the light travels. For example, when we submerge our legs in water, we can see that they appear shorter and closer. This is because the light travels in a straight line under water. But when it changes its medium to air, the original path changes because of the difference of densities of medium and light travels at different speeds.