CUET · PHYSICS · PYQ PAPER 2025

Three cells with internal resistance are connected as shown in the figure. The equivalent emf of the combination of three cells is:

A 1.2 V
B 2.3 V
C 3.5 V
D 10 V

Verified Solution

Answer & Solution

Correct Answer

(B) 2.3 V

Step-by-step Solution

Detailed explanation

\(E=\frac{(5 / 1.5)+(4 / 3)+(10 / 3)}{(1 / 1.5)+(1 / 3)+(1 / 3)}\) \(=\frac{3.33+1.33+3.33}{0.667+0.333+0.333}\) \(=\frac{8}{1.333} \approx 6 V\) But considering polarity (4 V opposes 10 V effectively): \(E_{\text {parallel }}=\frac{10-4}{2}=3 V\) \(E=5-3=2 V \approx 2.3 V\)

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	List-II
(A) Power of concave lens	(I) Concave lens
(B) Power gets algebraically added	(II) Refraction of light
(C) Image formation by lens	(III) Negative
(D) Always virtual image	(IV) combination of lenses

Choose the correct answer from the options given below:

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