Moving Charges in Uniform Magnetic Field—Acceleration182
Moving charged particles are released with a velocity (details listed below) at the point P (2 m, 2 m) in a
large region of space which has a uniform magnetic field in the +x direction. All these particles have the
same mass, and they are released individually into this field.
Rank from greatest to least the magnitude of the initial acceleration of these charged particles as they are
released from P.
Case
A
B
C
D
E
F
G
H
Charge
5 mC
5 mC
5 mC
5 mC
-10 mC
+10 mC
-10 mC
+10 mC
Speed
Direction
3 m/s
3 m/s
3 m/s
3 m/s
3 m/s
3 m/s
5 m/s
5 m/s
+x
-x
+y
-y
+y
-y
+y
-y
+y
P (2,2)
+x
Greatest
1 _____ 2 _____ 3 _____ 4 _____ 5 _____ 6 _____ 7 _____ 8 _____ Least
Or, the magnitude of the initial acceleration will be the same for all of these (but not zero). ___
Or, the magnitude of the initial acceleration will be zero for all of these. ____
Please carefully explain your reasoning.
How sure were you of your ranking? (circle one)
Basically Guessed
Sure
1
2
3
4
5
6
182
7
8
Very Sure
9
10
C. Hieggelke
Ranking Task Exercises in Physics
206
Electricity and Magnetism
Moving Charges in Uniform Magnetic Field—Change in Kinetic Energy183
Moving charged particles are released with a velocity (details listed below) at the point P (2 m, 2 m) in a
large region of space which has a uniform magnetic field in the +x direction. All these particles have the
same mass, and they are released individually into this field.
Rank from greatest to least the change in kinetic energy of these charged particles after they have
traveled 1 cm from P.
Case
A
B
C
D
E
F
G
H
Charge
5 mC
5 mC
5 mC
5 mC
-10 mC
+10 mC
-10 mC
+10 mC
Speed
Direction
3 m/s
3 m/s
3 m/s
3 m/s
3 m/s
3 m/s
5 m/s
5 m/s
+x
-x
+y
-y
+y
-y
+y
-y
+y
P (2,2)
+x
Greatest
1 _____ 2 _____ 3 _____ 4 _____ 5 _____ 6 _____ 7 _____ 8 _____ Least
Or, the change in kinetic energy will be the same for all of these (but not zero). ___________
Or, the change in kinetic energy will be zero for all of these. ___________
Please carefully explain your reasoning.
How sure were you of your ranking? (circle one)
Basically Guessed
Sure
1
2
3
4
5
6
183
7
8
Very Sure
9
10
C. Hieggelke
Ranking Task Exercises in Physics
207
Electricity and Magnetism
Pairs of Long Current Carrying Wires—Magnetic Field185
Shown below are several situations with two wires with currents of 2 A flowing out of (•) or into (X) the
page. Rank the magnetic field at point P from greatest to least. Count a downward pointing field as
negative and upward as positive. You may assume that each wire or point of interest is separated by the
same distance from the adjacent items and that each situation is independent of all others.
•
•
P
•
A
X
•
X
•
C
P
X
E
D
P
•
P
X
B
X
P
X
P
P
X
F
•
G
Greatest 1 _____ 2 _____ 3 _____ 4 _____ 5 _____ 6 _____ 7 _____ Least
Or, the magnetic field is the same in all cases. _______
Or, the magnetic field is zero in all cases. _______
Please carefully explain your reasoning.
How sure were you of your ranking? (Circle one)
Guessed
Sure
1
2
3
4
5
6
185
7
8
9
Very Sure
10
C. Davies, B. Diesslin, M. Nelson, G. Shepherd
Ranking Task Exercises in Physics
209
Electricity and Magnetism
Pairs of Equal Current Electromagnets—Force186
Eight pairs of electromagnets are shown below. The same current flows in each case. The pairs of
electromagnets are separated by the same distance, and they have the same length and diameter.
Carefully observe the orientation of the coil and direction of current flow.
Rank the forces between the magnets from the most attractive to the most repulsive.
A
B
C
D
E
F
G
H
Most Attractive 1____ 2____ 3____ 4____ 5____ 6____ 7____ 8____ Most Repulsive
Or, all of these pairs exert equal forces on each other. _________
Please carefully explain your reasoning.
How sure were you of your ranking? (circle one)
Basically Guessed
Sure
1
2
3
4
5
6
186
7
8
Very Sure
9
10
B. Emerson, C. Hieggelke
Ranking Task Exercises in Physics
210
Electricity and Magnetism
Electromagnets with Unequal Currents—Magnetic Field Between 189
Eight pairs of electromagnets are shown below. The current in the left electromagnet is one amp and the
current in the right one is two amps in each case. They are also separated by the same distance, and they
have the same length and diameter. Carefully observe the orientation of the coil and direction of current
flow.
Rank the magnetic fields at the midpoints between the electromagnets from the largest to the smallest.
(The direction to the right is positive, and –5 < -3.)
I = 1 amp
I = 2 amps
I = 1 amp
I = 2 amps
A
B
C
D
E
F
G
H
Largest 1_____ 2_____ 3_____ 4_____ 5_____ 6_____ 7_____ 8_____
Smallest
Or, the magnitude of the magnetic field is the same but not zero for all eight pairs.
Or, the magnitude of the magnetic field is zero for all eight pairs.
Please carefully explain your reasoning.
How sure were you of your ranking? (circle one)
Basically Guessed
Sure
1
2
3
4
5
6
189
7
8
Very Sure
9
10
B. Emerson, C. Hieggelke
Ranking Task Exercises in Physics
213
Electricity and Magnetism