Practice Test 2 (chapters 20, 21, 22, and 23 from Giancoli).
Mar3, 03
1. What is the strength of a magnetic field 4.0 cm from a long straight wire carrying 3.0 A of
current?
2. Two long parallel wires carry currents of 5.0 A and 8.0 A in the same direction. The wires are
separated by 0.30 m. Find the direction and the magnitude of magnetic force per unit length
between the two wires.
3. Which of the following is correct?
a. When a current carrying wire is in your right hand, thumb in the direction of the magnetic field
lines, your fingers point in the direction of the current.
b. When a current carrying wire is in your left hand, thumb in the direction of the magnetic field
lines, your fingers point in the direction of the current.
c. When a current carrying wire is in your right hand, thumb in direction of the current, your
fingers point in the direction of the magnetic field lines.
d. When a current carrying wire is in your left hand, thumb pointing in the direction of the
current, your fingers point in the direction of the magnetic field lines.
4. An electron experiences the greatest force as it travels 1.8x106 m/s in a magnetic field when it is
moving southward. The force is upward and of magnitude 2.2x10-12 N. What is the magnitude
and direction of the magnetic field?
5. A coil is wrapped with 15 turns of wire on a square frame with an area of 0.40 m2. A uniform
magnetic field is applied perpendicular to the plane of the coil. If the field changes uniformly from
0 to 0.75 T in 0.050 s, find the average value of the induced emf.
6. A flux through a coil changes from 4.0X10-5 Wb to 5.0X10-5 Wb in 0.10 s. What emf is
induced in this coil by this flux?
7. A loop lies flat on a table top in a region where the magnetic field vector points straight down.
The magnetic field vanishes suddenly. When viewed from above, what is the sense of the induced
current in this coil as the field fades?
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8. A circular coil lies flat on a horizontal table. A bar magnet is held above its center with its north
pole pointing down. The stationary magnet induces (when viewed from above)
9. An ideal transformer has 60 turns on its primary coil and 300 turns on its secondary coil. If 120
V is applied to the primary, what is the voltage in the secondary?
10. The E and B fields in electromagnetic waves are oriented
a. parallel to the wave's direction of travel, as well as to each other.
b. parallel to the waves direction of travel, and perpendicular to each other.
c. perpendicular to the wave's direction of travel, and parallel to each other.
d. perpendicular to the wave's direction of travel, and also to each other.
11. All electromagnetic waves travel through a vacuum at
a. the same speed.
b. speeds that are proportional to their frequency.
c. speeds that are inversely proportional to their frequency.
d. none of the above.
12. What is the wavelength for the carrier wave of 92.9 MHz?
13. A person’s face 30 cm in front of a concave shaving mirror. If the image is an erect image 1.5
times the size of the object. What is the focal length of the mirror?
14. An object is placed 15 cm from a concave mirror of focal length 20 cm. The object is 4.0 cm
tall. How tall is the image?
15. A light ray is incident on an air to glass interface at an angle of 45o and is refracted at an angle
of 30o to the normal. What is the index of refraction of the glass?
16. A beam of light traveling in air is incident on a slab of transparent material. The incident beam
and the refracted beam make angles of 400 and 260 to the normal. What is the speed of light in the
transparent material?
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17. What is the critical angle for light traveling from water (n = 1.33) into air?
18. An object 3 cm high is placed 20 cm from a convex mirror with a focal length of 8 cm. Find
the position of the final image and the magnification of the mirror.
19. An object is placed 30 cm from a converging lens with a focal length of 8 cm. Find the image
distance and the magnification of the lens.
20. An object is placed 30 cm from a diverging lens with a focal length of 8 cm. Find the image
distance and the magnification of the lens.
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