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Moving Charges and Magnetism — Physics STD 12 Science — Question

Rajasthan BoardEnglish MediumSTD 12 SciencePhysicsMoving Charges and Magnetism1 Mark
Question
Two statements are given-one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below.
  1. Both A and R are true and R is the correct explanation of A.
  2. Both A and R are true but R is NOT the correct explanation of A.
  3. A is true but R is false.
  4. A is false and R is also false.
Assertion (A): The magnetic field intensity at the centre of a circular coil carrying current changes, if the current through the coil is doubled.
Reason (R): The magnetic field intensity is dependent on current in conductor.
✓

Answer

  1. Both A and R are true and R is the correct explanation of A.
Explanation:
The magnetic field at the centre of circular coil is given by.
$\text{B}=\frac{\mu_0}{4\pi}\frac{2\pi\text{nl}}{\text{a}}$
So if current through coil is doubled then magnetic field is B' = 2B.
The magnetic field also get doubled. The magnetic field is directly proportional to the current in conductor.

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