કોઈ કોપર સુવાહકમાં મુક્ત સંખ્યા ઘનતા \(8.5 \times 10^{28} m^{-3}\) ઇલેક્ટ્રોનની અંદાજિત છે. આવા ઇલેક્ટ્રોનને 6 m લાંબા તારના એક છેડાથી બીજા છેડા સુધી ડ્રિફ્ટ થતા કેટલો સમય લાગશે ? તારના આડછેદનું ક્ષેત્રફળ \(1.0 \times 10^{-6} m^2\) અને તેમાંથી 1.5 A જેટલો પ્રવાહ વહે છે ?

A \(8.1 \times 10^4 s\)
B \(5.4 \times 10^4 s\)
C \(12.7 \times 10^4 s\)
D \(4.5 \times 10^4 s\)

Verified Solution

Answer & Solution

Correct Answer

(B) \(5.4 \times 10^4 s\)

Step-by-step Solution

Detailed explanation

(B)
\(\begin{aligned} I & =n Au _d e \\ \therefore \quad v_d & =\frac{ I }{n A e} \\ \therefore \quad \frac{l}{t} & =\frac{1}{n A e} \quad\left(\because v_d=\frac{l}{t}\right) \\ \therefore \quad t & =\frac{n A l e}{ I } \\ \therefore \quad t & =\frac{8.5 \times 10^{28} \times 1.0 \times 10^{-6}}{\times 6 \times 1.6 \times 10^{-19}} \\ \therefore \quad t & =54.4 \times 10^3 \\ \therefore \quad t & =5.44 \times 10^4 s\end{aligned}\)

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.

Same subject

Explore more questions on app

From GUJCET

Explore more questions on app