Download Magnetic Forces and Fields Test, 02-03 Pre-AP

Magnetic Forces and Fields Test Review, 2012
Equations are provided on test
1. Draw the magnetic field lines around a bar magnet, indicating the direction with arrows.
2. Draw the magnetic field lines around the Earth, indicating the direction with arrows.
3. Know the importance of Earth’s magnetic field. How does Earth’s magnetic field protect Earth?
4. On the atomic level, what is responsible for magnetic fields?
5. What is the aurora borealis caused by?
6. What force is stronger- gravitation or magnetic?
7. What surrounds every moving electric charge- an electric field, a magnetic field, or both?
7. Match the applications with the type of magnetic force:
Applications
Magnet force
Television screens
forces on electric charges
Speakers
forces on current carrying wires
8. Describe how an electric guitar uses magnets.
9. If a magnet is broken in half, is the result two magnets each with only one pole?
10. Which magnetic poles attract each other?
11. List two applications of a current induced in a wire due to a changing magnetic field.
12. What lies under the geographic North Pole- a magnetic North Pole or a magnetic South Pole?
13. What does a transformer do?
14. Who is credited with making the first motor, generator, and transformer?
15. What energy transformation takes place in a motor?
16. What energy transformation takes place in a generator?
17. How often does Earth’s magnetic field reverse its polarity?
18. What is created around every current carrying wire?
19. What is the name of Earth’s magnetic field?
20. What is the likely cause of Earth’s magnetic field?
21. Describe how to build a simple electromagnet.
22. What types of metals are magnetic?
23. What do Solar Storms produce?
Magnetic forces on moving charges. F = qv x B
q- charge (C), v- velocity (m/s), B- magnetic field (T)
Example:
23. The magnetic field within a cathode ray tube is 2.6 x 10-2 T. What force is exerted on electrons shot through
the tube at a speed of 2.4 x 107 m/s?
Magnetic forces on current-carrying wires. F = iL x B
i- current (A), L- length (m), B- magnetic field (T)
24. Example: If a wire experiences a magnetic force of 0.25 N while carrying 3 amps of current, how long is
the wire if Earth’s magnetic field is 1.9 x 10-5 T?
Pre-AP only:
Know the three right-hand rules.
Be able to solve problems where the magnetic force on a charge acts as a centripetal force, so that the charge
begins to move in a circular pathway. qv x B = mv2 /r
Use the right hand rule to predict the pathway of a charge as it moves into a magnetic field, such as seen in a
mass spectrometer.
25. A vertical wire carries current of 200 A that moves straight upward at a location in the Northern
Hemisphere where the magnitude of Earth’s magnetic field is 4.8 x 10-5 T and is at an angle of 20 degrees
below the horizontal. If the wire is 18.0 m long, what is the magnitude of the magnetic force on the wire?
26. What is the direction of the magnetic force on the wire?
27. An electron is accelerated through a potential difference of 5,000 V and enters a magnetic field moving
from West to East. If the magnetic field is pointed straight down into the ground and has a magnitude of 1.2 T,
what is the radius of the circle the electron moves in?
28. When the electron first enters the field, in what direction does it begin to curve?