Name _________________________________________ Period _______________

Magnetic Fields Mixed Review Solutions

On a separate sheet of paper, answer the following. Show all your work. Write down the appropriate formulas, rearrange the formula to solve for the unknown, then plug in numbers. Staple this sheet to your solution sheet.

1. A duck flying due east at 15 m/s passes over San Francisco, where the magnetic field of the Earth is directed north. The duck has a positive charge of . What is the magnetic force acting on the duck?

2. A proton moves at horizontally at a right angle to a magnetic field.

a. What is the strength of the magnetic field required to exactly balance the weight of the proton and keep it moving horizontally?

b. Should the direction of the magnetic field be in a horizontal or a vertical plane?

Must be horizontal at a right angle to the direction of travel, since only a horizontal field will produce a vertical force.

3. A neutral hydrogen atom loses its electron. Find the direction of the force on the ion moving through each magnetic field in the four figures below.

v v

a. b. c. d.

B v v

B

a. to the left

b. into the page

c. out of the page

d. up (towards the top of the page)

4. Find the direction of the force on an electron moving through each magnetic field in the above figure.

a. to the right

b. out of the page

c. into the page

d. down (towards the bottom of the page)

5. Find the magnitude of the magnetic force a magnet must generate to lift a 1 g nail off the table.

6. A thin 1.00 m long copper rod has a mass of 50.0 g. What is the minimum current needed in the rod to cause it to float in a magnetic field of 2.00 T?

7. A proton moves eastward in the plane of Earth’s magnetic equator so that its distance from the ground remains constant. What is the speed of the proton if Earth’s magnetic field points north and has a magnitude of ?

If its distance remains constant, then the magnetic force must be balancing gravity.

8. A proton travels with a speed of at an angle of 37° west of north. A magnetic field of 0.30 T points to the north. Determine the following:

a. The magnitude of the magnetic force on the proton.

b. The direction of the magnetic force on the proton.

Into the page

c. The proton’s acceleration.