The reason we can read print from any direction is that
- the white part of a page reflects light in all directions.
- letters emit black light in all directions.
- letters absorb black light from all directions.
A resistor is something placed in a circuit that totally blocks the flow of electrons.
A 10 micro-Coulomb charge is located in a 400 N/C electric field. What is the force experienced by the charge?
a. b. c.
1 x 10-3. N
4 x 10-3. N
4 x 10-3. N/C
The electrical force on a 2 C charge is 20 N. What is the value of the electric field at the location of the charge?
- 10 N/C
- 20 N/C
Electrons move in an electric circuit
- by being physically bumped by other electrons.
- by interacting with an established electric field.
- because the wires are so thin.
When light strikes the surface of a material like glass or water it is usually
- completely reflected back from the surface of the material.
- completely transmitted through the material.
- partially transmitted and partially reflected.
Laser light is emitted when excited atoms of a solid, liquid, or gas are stimulated to emit photons in phase.
An electroscope is charged positively, as shown by foil leaves that stand apart. As a negatively charged rod is brought close to the electroscope, the leaves
- spread farther apart.
- do not move.
- move closer together.
If you stand 1 m in front of a plane mirror your image appears
- less than 1 m behind the mirror.
- 1 m behind the mirror.
- more than 1 m behind the mirror.
Why does a farsighted person have trouble focusing on nearby objects?
- images form in front of retina (eyeball is too long)
- iris opening is too small
- image forms behind retina (eyeball is too short)
Two charges separated a distance of 1.0 meter exert a 2.0-N force on each other. If the charges are pushed to a separation of meter, the force on each charge will be
- 0.67 N.
- 6.0 N.
- 18.0 N.
Two charges separated by a distance of 1 meter exert a 20-N force on each other. If the charges are pulled to a 2 meter separation distance, the force on each charge will be
a. 5N. b. 10N. c. 40N.
Compared to gravity, the electromagnetic force is
- about the same strength.
- much stronger.
- much weaker.
What is the resistance of a toaster that uses 5 A of current when connected to a 120 volt power source? (Apply Ohm’s Law.)
- 5 ohms
- 24 ohms
- 600 ohms
A magnifying glass is a
- diverging lens.
- combination of diverging and converging lenses.
- converging lens.
When a wave slows down it
- bends away from the normal.
- bends toward the normal.
- continues in a straight line.