A rectangular loop of wire with dimensions 1.50 cm by 8.00 cm and resistance 0.8
ID: 1420026 • Letter: A
Question
A rectangular loop of wire with dimensions 1.50 cm by 8.00 cm and resistance 0.800 12 is being pulled to the right out of a region of uniform magnetic field. The magnetic field has magnitude 2.80 T and is directed into the plane of (Figure 1). At the instant when the speed of the loop is 3.00 m/s and it is still partially in the field region, what is the magnitude of the force that the magnetic field exerts on the loop? Express your answer with the appropriate units. What is the direction of the force that the magnetic field exerts on the loop?Explanation / Answer
a)
As the loop is pulled from the field, the flux through the loop decreases, causing an induced EMF whose magnitude is given by equation,
E = B*l*v
Because the inward flux is decreasing, the induced flux will be into the page, so the induced current is clockwise, given by equation
I = E / R
Because this current in the left-hand side of the loop is in a downward magnetic field, there will be a magnetic force to the left. To keep the rod moving, there must be an equal external force to the right, given by F = I*l*B
F = I*l*B = E/R*lB = (B*l*v / R)*l*B = B^2*l^2*B / R = (2.80)^2*(0.0150)*(3 ) / 0.800
F = 0.441 N
b) to the left