Which of these elements is not ferromagnetic?
2.Which of these is true about a magnetic field?
a. It has the same magnitude at every point
b.It has the same direction at every point
c. It points in the same direction as it would make a compass point
d. It has a magnitude at each point but no specific direction
3.Which of these is true about a bar magnet?
a. Its poles cannot be separated into two isolated poles
b. Its magnetic North Pole tends to point south
c Its poles attract or repel other magnets because of their net electric charge
d. It cannot attract iron objects unless they are permanent magnets
4. Suppose a magnetic field of .20 T is applied to the area within a circular loop of wire. The strength of the field is then changed to 0.10 T. By what factor is the magnetic flux changed?
5. A ferromagnetic material is subjected to a strong magnetic field and afterward acts as a permanent magnet. Why does this occur?
a. The magnetic field aligns the magnetic domains mainly in one direction.
b. Long range electric currents circulating in the iron make it magnetic
c. The magnetic field gives the ferromagnetic material an electric charge
d. The notion of the iron nuclei produces a magnetic field
6. What material is generally believed to have formed the first magnets to be discovered?
b. pure iron
7. Which of these is not true about magnetic field lines?
a. They form closed loops
b. they are closest together(densest) where the field is strongest
c. they have a different shape between like poles of two magnets than between two unlike poles.
d. they are perpendicular to the direction of the magnetic field at each point.
8.Why does a compass needle usually point north?
a. the right hand rule predicts a north pointing magnetic field from electrons carried eastward by westerly winds
b. they gyroscopic effect of the earth’s rotation makes the compass point north.
c. the net electric charge of the earth’s North Pole attracts one end of the compass needle
d. the earth is a magnet with its south magnetic pole located in the north
9. What shape do magnetic field lines have around a wire with a steady current in it?
a. lines parallel to the direction of the wire
b. straight lines radiating outward from the wire
c. concentric circles around the wire
d. spirals converging inward toward the wire
10. A maglev train requires which of the following?
a. A bolt of electricity must move between the track and the train.
b. The track and the train must have different magnetic poles
c. Magnetic poles must alternate between the track and train at nearly the speed of light
d. The track and the train must have the same magnetic poles
11. What produces the force for the torque that turns an electric motor?
a. electrical attraction to the North Pole of of the magnet
b. the electrical attraction of opposite charges
c. an induced electromotive force acting on a loop of wire
d. the force on a current in a magnetic field
12.Which of the following is responsible for the flow of electrons in a circuit?
a. any force exerted by electromagnetic radiation
b. electromotive force
c. the force of a magnetic field on a static charge
d. electrostatic force
13. Each side of a square loop of wire measures 2.0 cm. A magnetic field of 0.044 T perpendicular to the loop changes to zero in 0.10 s. What average emf is induced in the coil during this change?
a. 1.8 V
b. 0.00018 V
c. 0.088 V
d. 0.88 V
14What produces the emf in an electric generator
a. a coil rotating in a magnetic field to change its flux
b. an electric battery
c. an electric current in a coil that produces a torque on the coil to make it rotate
d. the repulsion between a positive charge and the North Pole of a magnet
15. The primary coil of a transformer has 1,00 turns of wire, and its secondary coil has 2,000 turns of wire. The input voltage is 140 V. What is the output voltage of the transformer?
a. 280 V
b. 60 V
c. 70 V
d. 420 V