please help 1-Magnetic resonance imaging (MRI) is a medical technique for produc

Question

please help

1-Magnetic resonance imaging (MRI) is a medical technique for producing pictures of the interior of the body. The patient is placed within a strong magnetic field. One safety concern is what would happen to the positively and negatively charged particles in the body fluids if an equipment failure caused the magnetic field to be shut off suddenly. An induced emf could cause these particles to flow, producing an electric current within the body. Suppose the largest surface of the body through which flux passes has an area of 0.022 m2 and a normal that is parallel to a magnetic field of 2.5 T. Determine the smallest time period during which the field can be allowed to vanish if the magnitude of the average induced emf is to be kept less than 0.010 V.

2- A magnetic field has a magnitude of 0.070 T and is uniform over a circular surface whose radius is 0.11 m. The field is oriented at an angle of

= 31°

with respect to the normal to the surface. What is the magnetic flux through the surface?

(a) Find the emf induced between the two sides of the car.
1 V

Explanation / Answer

1)For a uniform magnetic field B

= -d/dt(BAcos)

.010v=(2.5T)(.022m^2)/t

solving for t=5.5s

Ans- The field can be allowed to vanish in 5.5 seconds.

2)Magnetic flux is given by=B*A*cos(theta)

area A=pi*r^2

=0.07*3.14*0.11^2*cos31

=2.27*10^-9 Weber

Ans- the magnetic flux through the surface is 2.27*10^-9 Weber

3)According to the Faraday's Law:

emf = BLv = (5.3 x10^-5) (2.3 x 10^4) (7.6 x 10^3)
= 9264.4 volts

Ans- The motional emf generated between the ends of the wire would have been 9264.4 V

4)Given that condition, then the
voltage=velocity*B*length=21*5*10^-5*1.7
= 0.001857volt

Ans- The emf induced between the two sides of the car is 0.001857V

=

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