19. A square loop is placed onto the x-y plane. The square loop has 4 m sides and carries a current of I₁ = 7 A. If a straight, long conductor carrying a current I2 = 15 A is introduced and placed just above the midpoints of the two loop's sides, determine the net force acting on the loop. tch has been closed for a long-

A square loop whose sides are 6.0-cm long is made with copper wire of radius 1.0 mm. If a magnetic field perpendicular to the loop is changing at a rate of 5.0 mT/s, what is the current in the loop?

In a long, .straight, vertical lightning stroke, electrons move downward and positive ions move upward and constitute a current of magnitude 20.0 kA. At a location 50.0 m east of the middle of the stroke, a free electron drifts through the air toward the west with a speed of 300 m/s. (a) Make a sketch showing the various vectors involved. Ignore the effect of the Earth's magnetic field. (b) Find the vector force the lightning stroke exerts on the electron. (c) Find the radius of the electrons path. (d) Is it a good approximation to model the electron as moving in a uniform field? Explain your answer. (e) If it does not collide with any obstacles, how many revolutions will the electron complete during the 60.0-s duration of the lightning stroke?

A long, straight wire lies on a horizontal table and carries a current of 1.20 μA. In a vacuum, a proton moves parallel to the wire (opposite the current) with a constant speed of 2.30 × 104 m/s at a distance d above the wire. Ignoring the magnetic field due to the Earth, determine the value of d.