Investigators are researching the appearance of a strange movement of objects in

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 321 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 1.15 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?

Can you rule out the possibility that unusually strong magnetic fields are causing the strange behavior?

Explanation / Answer

= 40 rev/s
     = 40*2*pi rad/s
     = 251.33 rad/s

A = pi*r^2
    = pi*(1*10^-2)^2
    = 3.14*10^-4 m^2

maximum induced emf = BAN
1.15 = B*3.14*10^-4 * 321 * 251.33
B = 0.045 T
Answer: 0.045 T

This is weak magnetic field

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