Download Name: Mr. Rodriguez

Name:
Date:
Mr. Rodriguez
Physics is Life
Chapter 20 Problem Set #1
Conceptual Problems
1.
What is the major difference between electric charges and magnetic poles?
2.
What is happening within the Earth’s core that is causing the Earth to behave like a magnet?
3.
Define magnetic fields.
4.
Draw the magnetic field lines around a straight section of wire carrying a current horizontally to the left.
5.
In what direction are the magnetic field lines surrounding a straight wire carrying a current that is moving directly away from
you?
6.
A horseshoe magnet is held vertically with the north pole on the left and south pole on the right. A wire passing between the
poles, equidistant from them, carries a current directly away from you. In what direction is the force on the wire?
7.
6.
Will a magnet attract any metallic object, or only those made of iron? Why is this so?
Two iron bars attract each other no matter which ends are placed close together. Are both magnets? Explain.
o = 4 x 10-7Tm/A
B=onI
B=oI/2r
F=ILBsin
F=qVBsin
R=mv/qB
Computational Problems
1.
(a) What is the magnitude of the force per meter of length on a straight wire carrying an 5.40-A current when perpendicular to a
0.97-T uniform magnetic field? (b) What if the angle between the wire and field is 49.0°?
2. Calculate the magnitude of the magnetic force on a 200-m length of straight wire stretched between two towers carrying a 150-A
current. The Earth’s magnetic field of 5.0  10 5 T makes an angle of 75° with the wire.
3. How much current is flowing in a wire 7.30 m long if the maximum force on it is 0.950 N when placed in a uniform 0.0600-T
field?
4.
A 1.9-m length of wire carrying 4.9 A of current is oriented horizontally. At that point on the Earth’s surface, the dip angle of
the Earth’s magnetic field makes an angle of 36° to the wire. Estimate the magnitude of the magnetic force on the wire due to
the Earth’s magnetic field of 5.5  10 5 T at this point.
5.
The force on a wire carrying 8.05 A is a maximum of 1.18 N when placed between the pole faces of a magnet. If the pole faces
are 45.2 cm in diameter, what is the approximate strength of the magnetic field?
6.
Alpha particles of charge q  2e and mass m  6.6  10 27 kg are emitted from a radioactive source at a speed of
1.6 107 m s . What magnetic field strength would be required to bend them into a circular path of radius r  0.25 m?