IEMJEE Physics preparation: Field around a straight current — practice worksheet with answers

How to use this worksheet

This independent worksheet checks field around a straight current with a new problem, an explanation task and an interleaved related skill. It is not an official IEM question paper, a difficulty forecast or a prescribed timed examination.

Write an attempt first, then compare your method with the visible answers. Record whether a miss came from interpretation, a missing concept, execution or a condition you overlooked.

Question 1: apply the topic

If current triples at the same distance, how does B change?

Answer and checking point

It triples.

Check dimensions, direction and limiting behaviour. Ask whether the answer should increase or decrease when an input changes. A dimensional check is necessary in many calculations but cannot certify an omitted dimensionless coefficient or an inappropriate physical model.

Question 2: diagnose an approach

Explain why the following warning matters and identify the correction it calls for: Using an inverse-square distance law here confuses the long-wire field with a point-source field.

Model checkpoint: A long straight current produces circular magnetic-field lines with inverse-distance magnitude. Governing rule: B=μ₀I/(2πr) for the ideal long-wire model.

Question 3: transfer to faraday induction and lenz direction

Can steady unchanging flux induce an emf through this relation?

Answer: No. Its time derivative is zero.

This is an interleaved related-skill task, not a claim that the two topics have identical methods. Explain which idea changes when switching from the main topic to this one.

Review the attempt

Separate correct answers reached with a justified method from lucky guesses. Rework missed steps without looking at the answer, then use a fresh problem from an appropriate primary textbook or official paper. Do not use a small worksheet result as an admission cutoff, rank or readiness guarantee.

Official sources and verification

Sources checked on 26 October 2026. A source’s date, programme and campus limit which claims it supports. Official pages may change after review.

1. UEM — IEMJEE examination information

   Historical examination pattern; verify the current cycle on the central portal.

2. NTA — explicitly labelled JEE Main 2026 syllabus

   Historical PCM syllabus reference. Lessons and exercises are independently authored, not official IEMJEE papers or verified 2027 paper predictions.

3. NCERT — official textbook catalogue

   Primary textbook reference for checking school-level concepts. This directory does not certify the independent lesson or establish IEM examination weightage.

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