Tyndall phenomenon: when a beam of light passes through the colloid, a bright "path" appearing in the colloid can be observed from the vertical direction of the incident light. Which of the following belong to the Tyndall phenomenon? ['Flashlight hits the wall to form an aperture.', 'Light can change direction through water.', 'In the dense woods in the early morning, you can often see the beams of light passing through the branches and leaves.', 'The shadow of the blue sky and white clouds reflected in the clear lake.']