CUET · PHYSICS · PYQ PAPER 2025

The magnetic flux through a coil perpendicular to the plane is varying according to the relation \( \phi = (7t^3 + 3t^2 - 2t - 2) \, \text{Wb} \). If the resistance of the coil is \( 10\Omega \), the induced current through the coil at t = 2 s, will be

A 10A
B 9.4 A
C 4.9 A
D 7.8 A

Verified Solution

Answer & Solution

Correct Answer

(B) 9.4 A

Step-by-step Solution

Detailed explanation

\( \varepsilon = - \frac{d\phi}{dt} \) \( \varepsilon = - (21t^2 + 6t - 2) \) \( \varepsilon = - (21(2)^2 + 6(2) - 2) = - (84 + 12 - 2) = -94\,V \) \( I = \frac{|\varepsilon|}{R} = \frac{|-94|}{10} = 9.4\,A \)

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

1000 small water drops each of radius r and charge q coalesces together to form one big spherical drop. The potential of the big drop is larger than that of the smaller drop by a factor of:

CUET 2023 Medium

Match List I with List II

LIST I	LIST II
A. Cyclotron frequency	I. \(\frac{N A B}{K R}\)
B. Magnetic field due to a circular coil	II. \(\frac{q B}{2 \pi m}\)
C. Magnetic field inside a toroid	III. \(\frac{\mu_0 N I}{2 \pi R}\)
D. Voltage sensitivity	IV.\(\frac{\mu_0 I}{2 R}\)

Choose the correct answer from the options given below:

CUET 2023 Medium

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