CUET · PHYSICS · PYQ PAPER 2023

A wire of resistance \( 5 \, \Omega \) is drawn out so that its length is increased to thrice its original length. The new resistance would be :

A 10 \( \Omega \)
B 20 \( \Omega \)
C 40 \( \Omega \)
D 45 \( \Omega \)

Verified Solution

Answer & Solution

Correct Answer

(D) 45 \( \Omega \)

Step-by-step Solution

Detailed explanation

\( \frac{R_2}{R_1} = \left(\frac{L_2}{L_1}\right)^2 \) \( R_2 = 5 \, \Omega \times \left(\frac{3L_1}{L_1}\right)^2 \) \( R_2 = 5 \, \Omega \times 9 = 45 \, \Omega \)

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

The momentum of a photon associated with a radiation of frequency \(2 \times 10^{13} Hg\) is (Given: \(h=6.6 \times 10^{-34} J\) s and \(c=3 \times 10^8 m / s\) )

CUET 2025 Hard

Match List-I with List-II

LIST - I (Statement)	LIST - II (Energy band diagram)
(A) An intrinsic semiconductor at \(T =0 K\)	(I)
(B) An intrinsic semiconductor at \(T >0 K\) with thermally generated electron-hole pairs.	(II)
(C) Energy bands of n-type semiconductor at \(T >0 K\)	(III)
(D) Energy bands of p -type semiconductor at \(T >0 K\)	(IV)

Choose the correct answer from the options given below:

CUET 2025 Hard

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A	100cm	10cm
B	100cm	5cm
C	10cm	2cm
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