NEET · Physics · STD 12 - 3. current electricity

The resistance of a wire is \(R\; ohm\). If it is melted and stretched to \('n'\) times its original length, its new resistance will be

A \(\frac{R}{n}\)
B \(n^2R\)
C \(\;\frac{R}{{{n^2}}}\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\)
D \(nR\)

Verified Solution

Answer & Solution

Correct Answer

(B) \(n^2R\)

Step-by-step Solution

Detailed explanation

The resistance of a wire of length \(l\) and area \(A\) and resistivity \(\rho\) is given as

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

Match List \(- I\) with List \(- II:\)

List\(-1\) (Electromagnetic waves)	List\(-2\) (Wavelength)
\((a)\) \(AM\) radio waves	\((i)\) \(10^{-10}\,m\)
\((b)\) Microwaves	\((ii)\) \(10^{2}\,m\)
\((c)\) Infrared radiations	\((iii)\) \(10^{-2}\,m\)
\((d)\) \(X-\)rays	\((iv)\) \(10^{-4}\,m\)

Choose the correct answer from the options given below:

NEET 2022 Easy

Explore more questions on app

From NEET

Explore more questions on app