Magnetic Fields

The SI unit of magnetic field strength is the

• watt

• tesla

• coulomb

• newton

The magnetic lines of force around a straight currentcarrying conductor are

• parallel to conductor

• opposite to the conductor

• in the same direction of the current

• circular

Parallel and equidistant lines of forces indicate that the magnetic field is

• very high

• very low

• uniform

• non-uniform

A current flows in a conductor from east to west. The direction of the magnetic field at a point above the conductor is towards ___.

• north

• south

• east

• west

The strength of Earth’s magnetic field has an average value of about ____ T.

A power line lies along the east–west direction and carries a current of 10 A. The force acting on a 1 m segment due to Earth’s magnetic field of 10^-5 T is ___N.

• 10^-2

• 10^-4

• 10^-3

• 10^-5

When a conductor is carrying a current, there will be no force acting on it when the conductor is placed in a magnetic field ___ to it.

• parallel

• perpendicular

• at an angle of 90°

• at an angle of 60°

An electric charge, q, moves with a constant velocity, v, parallel to the lines of force of a uniform magnetic field, B. The force experienced by the charge is

• Bqv

• zero

An MRI machine uses this to align atoms

• a powerful electric field

• a weak electric field

• a powerful magnetic field

• a weak magnetic field

Which of the following magnetic properties is exhibited by Earth?

• has a magnetic north and a magnetic south pole

• has magnetic field lines that are uniformly spaced

• attracts and repels magnetic compass needles.

• repels all cosmic rays