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

0.18216 T

Step-by-step explanation:

N = Number of turns = 219

A = Area =
`\pi r^2`

r = Radius = 1 cm

`\omega` = Angular speed =
`40* 2\pi`

Maximum emf is given by

`\epsilon=NBA\omega\\\Rightarrow B=(\epsilon)/(NA\omega)\\\Rightarrow B=(3.15)/(219* \pi 0.01^2* 40* 2\pi)\\\Rightarrow B=0.18216\ T`

The strength of the magnetic field is 0.18216 T