19.2 Physics

Question 1

What did scientists suspect in the 1700’s?

Answer 1

That there was a relationship between electricity and magnetism

Question 2

Who devised a method to study the relationship between electricity and magnetism, and when?

Answer 2

Danish physicist Hans Christian Oersted in 1820

Question 3

What specific discovery did Hans Christian Oersted publish, and how did he come about it?

Answer 3

A compass compass needle near a current carrying wire is deflected from it’s north-south orientation. He came across this following a lecture to his advanced class.

Question 4

A long, straight current carrying wire…

Answer 4

has a cylindrical magnetic field

Question 5

When compasses surround a wire that has no current, what is observed?

Answer 5

All the needles point in the same direction

Question 6

When compasses surround a wire that has a strong, steady current, what is observed?

Answer 6

All the needles defletc in directions tangent to the concentric circles around the wire.

Question 7

What is B?

Answer 7

The magnetic field induced by a current.

Question 8

What can the right hand rule be used to determine?

Answer 8

It can be used to determine the direction of the magnetic field

Question 9

If the wire is grasped in the right hand with the thumb in the direction of the current…

Answer 9

the four fingers will curl in the direction of B.

Question 10

The lines of B form…

Answer 10

concentric circles around the wire

Question 11

B is proportional to what, and inversely proportional to what?

Answer 11

B is proportional to the current, and inversely proportional to the distance.

Question 12

The right hand rule can also be applied to find the direction of what?

Answer 12

The direction of the magnetic field of a current carrying loop, called a solenoid.

The field within the loop points in the same direction regardless of

where; it points upward.

Question 13

What is a solenoid?

Answer 13

It’s a long, helically wound coil of insulated wire

Question 14

How do solenoids produce a strong magnetic field?

Answer 14

They do so by combining several loops

Question 15

Why is a solenoid important in many applications?

Answer 15

It’s because it acts as a magnet when it carries a current

Question 16

When does the magnetic field strength increase in a solenoid?

Answer 16

The strength of the field increases when the current increases, as well as when the number of coils per unit length increases.

All three of these are directly proportional

Question 17

How can the magnetic field strength of a solenoid be further increased?

Answer 17

It can be increased by inserting an iron rod in the center of the coil; this device is often called an electromagnet.

Question 18

Contrast between the field lines inside the solenoid, and the field lines outside of it.

Answer 18

The field lines inside the solenoid point in the same direction, are nearly parallel, are uniformly placed, and are close together (it’s strong and nearly uniform). The field outside the solenoid is nonuinform and much weaker than the internal field.

Question 19

The solenoid resembeld what?

Answer 19

It resembles a bar magnet; it has north and south poles.

Question 20

What is the shape of the magnetic field produced by a straight current-carrying wire?

Answer 20

Concentruc circles

Question 21

Why is the magnetic field inside a solenoid stronger than the magnetic field outside?

Answer 21

Distance and magnetic field ae inversely proportional

Question 22

If electrons behave like magnets, then why aren’t all atoms magnets?

Answer 22

A magnetic field does not exert a net force on a stationary charged particle.