Free Magnetic Flux Density MCQs with Answers
12 Magnetic Flux Density MCQs from Physics, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
12 questions · page 2 of 2
11. A current carrying coil placed in a uniform magnetic field experiences
- A. a net force that accelerates it across the field
- B. a torque that tends to align its plane perpendicular to the field
- C. neither force nor torque
- D. a force along the field lines
Explanation: The forces on opposite sides of the coil are equal and opposite, so they cancel and there is no net translational force, but because they act along different lines they form a couple that rotates the coil. The rotation continues until the plane of the coil is perpendicular to the field, at which point the torque is zero. A motor uses a commutator to reverse the current at that instant so rotation continues.
Correct answer: a torque that tends to align its plane perpendicular to the field12. The Earth's magnetic field is approximately
- A. 5 tesla
- B. 50 microtesla
- C. 50 millitesla
- D. zero at the equator
Explanation: At around 50 microtesla the geomagnetic field is weak enough that a compass needle needs to be delicately mounted to respond to it, and strong enough to deflect charged particles from the Sun. The field is horizontal near the magnetic equator and dips steeply near the poles. A laboratory electromagnet is thousands of times stronger.
Correct answer: 50 microtesla