Consider the system pictured in the figure below. A 13.5-cm horizontal wire of m
ID: 1442191 • Letter: C
Question
Consider the system pictured in the figure below. A 13.5-cm horizontal wire of mass 13.5 g is placed between two thin, vertical conductors, and a uniform magnetic field acts perpendicular to the page. The wire is free to move vertically without friction on the two vertical conductors. When a 5.45-A current is directed as shown in the figure, the horizontal wire moves upward at constant velocity in the presence of gravity. What forces act on the horizontal wire? magnetic force electric force gravitational force Under what condition is the wire able to move upward at constant velocity? Find the magnitude and direction of the minimum magnetic field required to move the wire at constant speed. magnitude direction What happens if the magnetic field exceeds this minimum value?Explanation / Answer
Solution:
a) Magnetic force & Gravitational force act on the wire.
b) When Magnetic field B is up , the gravity force mg balances it. So the net force will be zero. And the wire can move up with constant velocity.
c) The magnetic force on a wire of length L with a current I flowing in it is BIL = mg
B = mg / IL = (0.0135) (9.8) / (5.45)(0.135) = 0.18 T
direction is Upwards.
d) If magnetic field exceeds minimum value, magnetic force will be greater than gravity force. So the wire accelerates upwards.