1. [B] Light changes its path because light only travels in straight line. Speed of light is different in different media. As the medium changes, the light has to choose a path of minimum time. Hence, the direction of the light changes. This phenomenon is known as refraction of light.

    [B] Light changes its path because light only travels in straight line.
    Speed of light is different in different media. As the medium changes, the light has to choose a path of minimum time.
    Hence, the direction of the light changes. This phenomenon is known as refraction of light.

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  2. Sound waves are called mechanical waves because they require a material medium for their propagation.

    Sound waves are called mechanical waves because they require a material medium for their propagation.

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