CUET · PHYSICS · PYQ PAPER 2025

A current of 2 A flows through a 2 \( \Omega \) resistor when connected with a cell. When the resistance is replaced by 10 \( \Omega \), a current of 0.5 A flows. The internal resistance of the cell is

A 1/3 \( \Omega \)
B 1 \( \Omega \)
C 3/2 \( \Omega \)
D 2/3 \( \Omega \)

Verified Solution

Answer & Solution

Correct Answer

(D) 2/3 \( \Omega \)

Step-by-step Solution

Detailed explanation

\(E = I_1(R_1+r) \Rightarrow E = 2(2+r)\) \(E = I_2(R_2+r) \Rightarrow E = 0.5(10+r)\) \(2(2+r) = 0.5(10+r)\) \(4+2r = 5+0.5r\) \(1.5r = 1\) \(r = \frac{1}{1.5} = \frac{2}{3} \, \Omega\)

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

Match List-I with List-II:

List-I (Application)	List-II (Electromagnetic Waves)
(A) Used in radiography	(I) UV rays
(B) Detection by stimulating nerve endings of the human retina	(II) Microwaves
(C) Water purification	(III) Visible light
(D) Radar communication	(IV) X rays

Choose the correct answer from the options given below:

CUET 2025 Easy

Two point charges, +2 \( \mu \text{C} \) and -3 \( \mu \text{C} \), are separated by a distance of 20 cm in the air. At what point between the two charges and on the line joining the two charges is the electric potential zero?
(Take the potential at infinity to be zero)

CUET 2023 Hard

Explore more questions on app

From CUET

Explore more questions on app