Final answer:
When a straight pencil is partially immersed in water, it appears bent due to the phenomenon of refraction of light.
Step-by-step explanation:
When a straight pencil is partially immersed in water, it appears bent due to the phenomenon of refraction of light. Refraction occurs because light waves travel at different speeds in different mediums. The change in the speed of light as it passes from air to water causes the pencil to appear bent at the interface between the two mediums.
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