Problem 75-2
Source: Problem 3 - page 1076 - KNIGHT, Randall D. - Book:
Physics - A Strategic Approach - 2ª Edição - Ed. Bookman - 2009.
A 10 cm long wire is pulled along a conductive U-shaped rail in the presence of a perpendicular magnetic field. The total resistance of the wire and the rail is 0.20 Ω. Pulling the wire with a force of 1.0 N causes 4 W of power to dissipate in the circuit.
a) What is the speed of the wire when pulled with a force of 1.0 N?
b) What is the intensity of the magnetic induction field?
Solution of the Problem 75-2
Reviewing the equations eq. 75-08 and eq. 75-09, we can easily verify the equality below:
From this equation, we take the value of the wire speed, or:
As we know the value of the wire speed, making an algebraic manipulation in eq. 75-09 and replacing
with the numerical values, we obtain:
Performing the calculation, we obtain for the value of B the following:
