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物理 · 共 52 題 · 點擊選項即時核對答案

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51.

Ray falling on a convex lens with possible emergent rays P, Q, R and S; F is the principal focus

A ray of light falls on a convex lens as shown in the figure. $F$ is the principal focus of the lens. Which of the following represents the path of the emergent ray ?

52.

A convex lens is used to form an image of a bright object on a screen. The effect of covering the top half of the lens with a card is to