Question
For a metal of work function 6.6 eV, which of the following wavelengths of incident radiation does not give rise to the photoelectric effect ? (Take Planck's constant as 6.6 10^ -34 J s)
NEET
Physics
Dual Nature of Matter
2026
NEET 2026 (Cancelled)
NEET Physics Question (2026) — Solution
Options
- A. 100 nm
- B. 150 nm
- C. 200 nm
- D. 50 nm
Answer
C. 200 nm
Step-by-step solution
The threshold wavelength _0 is given by _0 = hc . Substituting the given values: _0 = 6.6 10^ -34 3 10^8 6.6 1.6 10^ -19 _0 = 3 1.6 10^ -7 m _0 = 1.875 10^ -7 m = 187.5 nm For the photoelectric effect to take place, the wavelength of incident radiation must be less than or equal to the threshold wavelength ( _0). Among the given options, 200 nm is greater than 187.5 nm. Thus, radiation of wavelength 200 nm will not give rise to the photoelectric effect. Answer: 200 nm
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