ધાતુની સીમાંત (થ્રેશોલ્ડ) આવૃત્તિ \(f _0\) છે.જયારે \(2 f _0\) આવૃત્તિ ધરાવતો પ્રકાશ ધાતુની તકતી ઉપર આપાત થાય છે ત્યારે ઈલેક્ટ્રોનનો મહત્તમ વેગ \(v_1\) મળે છે.જયારે આપત વિકિરણની આવૃત્તિ વધારીને \(5f_0\) કરવામાં આવે છે ત્યારે ઉત્સર્જાતા ઈલેક્ટ્રોનનો વેગ \(v_2\) થાય છે.\(v_1\) અને \(v_2\)નો ગુણોતર \(..............\) થશે.

A \(\frac{v_1}{v_2}=\frac{1}{2}\)
B \(\frac{v_1}{v_2}=\frac{1}{8}\)
C \(\frac{v_1}{v_2}=\frac{1}{16}\)
D \(\frac{v_1}{v_2}=\frac{1}{4}\)

Verified Solution

Answer & Solution

Correct Answer

(A) \(\frac{v_1}{v_2}=\frac{1}{2}\)

Step-by-step Solution

Detailed explanation

\(K _{\max }= hf - hf _0\) For \(f =2 f _0\) \(\frac{1}{2} m V _1^2=2 h f _0- hf _0= hf f _0\) For \(f =5 f _0\) \(\frac{1}{2} m V _2^2=5 h \textrm {f } _ { 0 } - hf _0=4 h _0\) \(\frac{ V _1}{ V _2}=\frac{1}{2}\)

Apply the relevant identity from the chapter and substitute the values established in the previous step, keeping the original constraint in view.

Use the simplified expression to isolate the unknown, then plug the result back into the question setup to confirm the working is internally consistent.

Cross-check against a boundary or limiting case. Both the dimensional balance and the qualitative behaviour at the extreme should agree with the candidate answer.

Combine the steps above to identify the correct option. The remaining choices each fail at least one of the consistency, dimensional, or boundary checks.

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