25 verified questions · ~28 minutes · answer key checked against the official NTA final key across multiple sources. Text-only questions (diagram-based excluded until they can be shown properly).
A long straight wire of radius a carries a steady current I. The current is uniformly distributed across its cross section. The ratio of the magnetic field at a/2 and 2a from the axis of the wire is:
If ε₀ is the permittivity of free space and E is the electric field, then ε₀E² has the dimensions:
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