Question

Investigators are researching the appearance of a strange movement of objects in what the local community considers a haunted house.
The owners of the house attribute the cause to poltergeists; others blame overly strong magnetic fields could be the cause.

As a scientific investigator of paranormal claims, you decide to investigate. You will start by focusing on magnetic fields.


Using a coil made of 219 turns of single-strand copper wire, you use a motor to rotate the coil at a constant angular speed of 40.0 revolutions per second at various orientations and locations throughout the room. In one particularly signficant orientation, you notice a maximum induced voltage of 3.15 V appearing in the coil.


If the radius of the coils is 1.00 cm, how strong was the magnetic field that produced this EMF?

Answer 1

Answer:

0.18216 T

Explanation:

N = Number of turns = 219

A = Area = $\pi r^2$

r = Radius = 1 cm

$\omega$ = Angular speed = $40\times 2\pi$

Maximum emf is given by

$\epsilon=NBA\omega\\\Rightarrow B=\dfrac{\epsilon}{NA\omega}\\\Rightarrow B=\dfrac{3.15}{219\times \pi 0.01^2\times 40\times 2\pi}\\\Rightarrow B=0.18216\ T$

The strength of the magnetic field is 0.18216 T