Modern Physics> When a metallic surface is illuminated wi...

When a metallic surface is illuminated with radiation of wavelength lambda the stopping potential is v. If the same surface is illuminated with rafiation of wavelength 2lambda the stopping potential is v/4. The threshold wavelength for metallic surface? A. 3 lambdaB. 4lambdaC. 5 lambdaPlease give a detailed explanation.

kanika , 7 Years ago

Grade 12th pass

2 Answers

Adarsh

let threshold wavelength be λ_o. Ans work function be Φ.

so, eV₀ = hc/λ – Φ …..... (1)

eV₀/4 = hc/2λ – Φ …........ (2)

on dividing we get , hc/λ – Φ = 2hc/λ – 4Φ

=> 3Φ=hc/λ

=> Φ = hc/3λ … so λ₀=3λ.

Hence 3λ is the threshold wavelenght ..

Approved

Last Activity: 7 Years ago

Yash Chourasiya

Dear Student

Case(i),eV = hc/λ − hc/λ₀..........(i)
Case (ii),eV4 = hc/2λ − hc/λ₀
or eV = 4hc/2λ − 4hc/λ₀.......(ii)

From equation (i) & (ii), we get
λ₀= 3λ

I hope this answer will help you.
Thanks & Regards
Yash Chourasiya

Last Activity: 5 Years ago

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Modern Physics> When a metallic surface is illuminated wi...

kanika , 7 Years ago

Adarsh

Yash Chourasiya

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