Light moves in straight lines | Light | Physics

This activity involves using a candle as a light source, and two movable openings on stands that can be placed at any point on the table. Start with placing the candle near a screen and seeing that light travels from the candle and illuminates the screen. Place an opening next to the candle, and it can be seen that only the light that passes through it illuminates the screen, in a much smaller area. Placing the second opening blocks the light and no light passes through, unless care is taken to line up the openings with the candle. This proves that light travels in straight lines, and unless a straight path is available, its progress is blocked.