Chipola Junior College-PHY 1054

Magnetic Field Practice

1.      Consider the current segments shown below. They lie in a magnetic field of 2.8 T which points into the paper. A current of 5 A runs through the wire segments in the direction shown. Find the net force on the wire segments.

 

 

 

 

 

 

 


2.      A straight, stiff, horizontal wire of length 0.40 m and mass 0.1 kg is connected to a source of EMF by light, flexible leads. A magnetic field of 2.66 T is applied horizontally (parallel to the ground) in an orientation perpendicular to the wire.

a) Draw a diagram of the above situation showing the magnetic field going into the board. Also show in your diagram the direction of the current in order to produce an upward force and thus be able to float the wire.

b) Find the current necessary to float the wire, that is, the current flowing in the wire such that the magnetic force balances the weight.

c) What is the force on the wire if a current of 10 A is introduced into the wire?

 

3.      Two long straight wires are spaced a distance of 0.4 m apart, as shown below. The wires carry different currents in opposite directions as indicated in the diagram.

a) Find the direction and magnitude of the magnetic field at point P, which is located midway between the two wires. Briefly explain how you determined the direction of the field.

b) Find the direction and magnitude of the magnetic field at point Q, which is located a distance of 0.3 m below the lower wire.

c) Calculate the force per length between the two wires by considering the force of the magnetic field of one wire on the current in the other wire. In other words, i) first calculate the field of one current at the position of the other current, and then ii) find the force on a 1m section.

 

 

 

4.  A current carrying wire is bent into two segments of length 0.5 m and height 0.2 m, which lie in the xy plane as shown below. There is a uniform magnetic field Bo=3 T k perpendicular to the plane of the loop.

y
 
                       

 

 

 

 

 

 

 

 

 


Find the net force( magnitude and direction) acting on the wire.

 

5.      Consider a 1000 kg vehicle which levitates using magnetic forces. The vehicle is in a uniform field of 7 x 10-5 T pointing north ( B = -Bo k) due to the earth’s field. The ship can generate a current running along a 5 m wire from the back of the ship to the front of the ship You must draw the directions of all quantities or use proper unit vectors to clarify your solutions. Assume the vehicle is oriented for maximum force.

a)      In what direction must the ship be pointing in order to achieve the maximum force?

b)      How much current must be provided in order to levitate (or float) the vehicle?

c)      How much current must flow to produce a downward acceleration of a=-15 m/s2 j?

d)      Find the net force on a charge of 1 Coulomb if it thrown out of the window with a velocity of v = (200i + 200j) m/s.

 

6. Two long straight wires are spaced a distance of 0.4 m apart, as shown below. The wires carry different currents in opposite directions as indicated in the diagram.

 

a) Find the direction and magnitude of the magnetic field at point P, which is located midway between the two wires. Briefly explain how you determined the direction of the field.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

b) Find the direction and magnitude of the magnetic field at point Q, which is located a distance of 0.5 m below the lower wire.

 

c) Find the direction and magnitude of the magnetic field at point R, which is located a distance of 0.2 m above the upper wire.

 

e)      Calculate the force per length (magnitude and direction) between the two wires by considering the force of the magnetic field of one wire on the current in the other wire. In other words, first calculate the field of one current at the position of the other current, and then find the force on a 1m section of wire.

 

7. A new form of car uses magnetic forces to propel it horizontally. The diagram below shows a car in the Earth's magnetic field, which has a strength of 1x10-4 T pointing out of the paper. A 3 m wire can be oriented horizontally under the car in any direction.

 

 

 

 

 

 

 

 


a)Draw a diagram of the above situation, indicating clearly the direction of the current necessary for a maximum acceleration in the positive x-direction.

b)How much current must flow through the wire for an acceleration of 2.5 m/s2 to the right?

 

8. Two current carrying wires are set-up as shown below. Remember to include the direction on all vector quantities.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 


a)Calculate the magnetic field at point P1, which is located a perpendicular distance of 2.8 m from I1, between the two wires

b)Calculate the magnetic field at point P2, which is located a perpendicular distance of 3.2 m below I2.

c)      Find the force on current I1 due to I2.

 

9. Consider the straight current segments shown below. Note that they run either horizontally, or vertically with the dimensions shown. Each segment carries a current I=3.7 A and the magnetic field Bo points straight up.

 

 

 

 

 

 

 

 

 

 

 

 


a)      What is the net force on the wire segments if they are put in a magnetic field applied vertically upward as shown in the figure?

b)      What is the net force on the wire segments if they are put in a magnetic field applied horizontally to the right?