Physics · 2026
JEE Main · 21 January 2026, Shift 1 · Q47
A collimated beam of light of diameter 2 mm is propagating along x -axis. The beam is required to be expanded in a collimated beam of diameter 14 mm…
A collimated beam of light of diameter $\displaystyle 2$ mm is propagating along $\displaystyle x$-axis. The beam is required to be expanded in a collimated beam of diameter $\displaystyle 14$ mm using a system of two convex lenses. If first lens has focal length $\displaystyle 40$ mm, then the focal length of second lens is $\displaystyle \_\_\_\_$ mm.
Official answer
From NTA’s final answer key for this paper.
280
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JEE Main 2026 Physics question, with the answer from NTA’s final answer key. Where our answers come from.