λhc=W λlongest =Whc=4.0×1.6×10−196.6×10−34×3×108 ⇒λlongest ≈310 nm.
JEE Main 2004 — Physics Modern Physics
The work function of a substance is 4.0eV. Then longest wavelength of light that can cause photoelectron emission from this substance approximately
Held on 30 Apr 2004 · Verified 6 Jul 2026.
540 nm
400 nm
310 nm
220 nm
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