JEE Main 2026 — Dual Nature of Matter Question with Solution
JEE Main 2026 (24 January Shift 2)
Question
When a light of a given wavelength falls on a metallic surface the stopping potential for photoelectrons is 3.2 V. If a second light having wavelength twice of first light is used, the stopping potential drops to 0.7 V. The wavelength of first light is m.
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Show full solutionCorrect option: A
Correct answer
A
Step-by-step explanation
Using Einstein's photoelectric equation with stopping potentials:
For first light, .
For second light with (so ): .
From given values: gives .
Thus m.
For first light, .
For second light with (so ): .
From given values: gives .
Thus m.
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This is a previous-year question from JEE Main 2026, covering the Dual Nature of Matter chapter of Physics. PrepSharp catalogues every PYQ from JEE Main with a verified answer key and step-by-step solution prepared by IIT alumni — so you can search by chapter, topic or year and revise efficiently.