1. According to Faraday's law of induction, the magnitude of the induced emf in a circuit equals the absolute value of the time rate of change of the magnetic flux through the circuit. In this definition, which statement about the emf is true?
It is always equal to 1.
It is always positive.
It is always negative.
It is always equal to zero.
2. An old battery has an emf of 6.0 V and an internal resistance of 1200 A?©. The battery supplies 2.5 mA to a lightbulb. What is its terminal voltage?
zero
9.6 V
3.0 V
6.0 V
3. Let B = the magnitude of the magnetic field of an EM wave; f = the frequency of the wave; and c = the speed of light. What is the magnitude of the electric field E?
cB
fB
4. A radiating body has a Kelvin temperature T0, and its surroundings are at When the Kelvin temperature of the radiating body increases to 2T0, the net rate of its radiation increases by a factor of 39. What is T0?
523 K
540 K
567 K
512 K
5. Which event results directly from charged particles moving in helical paths within a magnetic field?
the formation of a tail on a comet
a volcanic eruption
an aurora in earth's atmosphere
nuclear fusion in stars
6. A plastic rod is rubbed with fur. How do both objects become charged?
Electrons are created in the rod.
Electrons are transferred from the fur to the rod.
Electrons from the air are absorbed into the rod as the fur releases electrons into the air.
Electrons are destroyed in the fur.