Question:
Every lens has _____ focal points.
Every lens has _____ focal points.
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Since light can travel through a lens in both directions, lenses always have two principal foci located symmetrically on either side.
Updated On: May 18, 2026
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The Correct Option is D
Solution and Explanation
Concept:
A lens refracts light from both sides. Therefore, it possesses two principal foci.
Explanation:
One focal point lies on the left side of the lens and the other lies on the right side.
• When parallel rays come from the left side, they converge or appear to diverge from the focus on the right side.
• When parallel rays come from the right side, they converge or appear to diverge from the focus on the left side. Thus, every lens has:
• First principal focus ($F_1$)
• Second principal focus ($F_2$) Hence, every lens has two focal points.
• When parallel rays come from the left side, they converge or appear to diverge from the focus on the right side.
• When parallel rays come from the right side, they converge or appear to diverge from the focus on the left side. Thus, every lens has:
• First principal focus ($F_1$)
• Second principal focus ($F_2$) Hence, every lens has two focal points.
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