1141 Questions & Blanks

Question 1

The three laws of magnetism

Answer 1

Either pole of a magnet attracts nonmagnetic ferromagnetic substances
Like magnetic poles repel one another, unlike attract.

Question 2

Why does a compass needle point north?

Answer 2

It aligns itself with Earth’s magnetic field

Question 3

Three ways to disrupt the alignment of magnetic domains

Answer 3

heat
interaction with another magnetic field
mechanical action

Question 4

Use inverse square law (m1m2/r^2) for magnet problems.

Answer 4

.

Question 5

Compare the similar properties of magnetism and electricity

Answer 5

Magnetism has two opposite poles–and electricity–two opposite charges. Like charges/poles repel, but unlike attract.
The forces of attraction and repulsion in each follow the inverse square law.

Question 6

Left- hand rule for magnetic fields around current-carrying wires.

Answer 6

When a wire is grasped in the left hand so that the thumb points in the direction of the electron flow, the fingers will be pointing in the direction that the magnetic lines of force are flowing.

Question 7

Each electron in the atom can be considered a _________, which _____________

Answer 7

tiny electric current

generates a magnetic field

Question 8

A wire coiled in the shape of a cylinder is called a _________

Answer 8

solenoid

Question 9

Left-hand rule for the magnetic field inside a solenoid

Answer 9

When a coil is grasped in the left hand so that the fingers point in the direction of the electron flow in the wires, then the extended thumb will point in the direction of the internal lines of force and toward the north pole of the coil

Question 10

Left-hand rule for the deflecting force on a current-carrying wire in a magnetic field.

Answer 10

Point the thumb of the left hand in the direction of the current and the fingers in the direction of the magnetic lines of force. The palm of the hand then faces the direction of the deflecting force acting upon the wire.

Question 11

Three ways to induce an electric current with a magnetic field.

Answer 11

moving a magnet near a stationary wire
moving a wire near a stationary magnet
by holding both magnet and wire stationary, but causing the magnetic field to expand and contract

Question 12

Why does a light bulb glow as soon as a circuit is completed, even though electrons move rather slowly through the circuit?

Answer 12

Because all free electrons in the wire begin to move the instant the circuit is completed

Question 13

Measured in volts

Answer 13

electromotive force

Question 14

Compare the transfer of electrical energy by electromotive force to the transfer of gravitational energy.

Answer 14

Electrical energy travels from a region of higher electrical potential to a region of lower electric potential in the same way that gravitational energy travels from a region of higher gravitational potential to a region of lower gravitational potential.

Question 15

SI unit for resistance

Answer 15

ohms

Question 16

Georg Simon Ohm was the first person to make a systematic study of ____

Answer 16

current, electric potential, and resistance

Question 17

What two factors control the amount of current supplied by an electrical source?

Answer 17

electromotive force

resistance of the circuit

Question 18

Ohm’s law

Answer 18

Current is directly proportional to electric potential and inversely proportional to the resistance.

Question 19

The four factors that determine the resistance in a current-carrying wire.

Answer 19

type of material
length of wire
diameter of wire
temperature

Question 20

I = V/R

Answer 20

current(amperes) = electrical potential(volts)/resistance(ohms)

Question 21

heat energy = current(amperes) x time(seconds) x electric potential(volts)

Answer 21

0.239calories per joule