Key Idea Only signals having wavelength less than threshold wavelength will be detected. Energy E=hv=hλcλ=Ehc ⇒λ=Ehc Substituting the values of and in the above equation λ=2.5×1.6×10−196.6×10−34×3×108=5000A˚ As 4000A˚<5000A˚ Signal of wavelength 4000A˚ can be detected by the photodiode.
A p-n photodiode is fabricated from a semiconductor with a band gap of 2.5 eV. It can detect a signal of wavelength
NEET UG 2009 — Physics Modern Physics
2009mcqeasy
A p−n photodiode is fabricated from a semiconductor with a band gap of 2.5eV. It can detect a signal of wavelength
Official previous-year question
Held on 30 Apr 2009 · Verified 9 Jul 2026.
Options
- A
6000A˚
- B
4000 nm
- C
6000 nm
- D
4000A˚
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