Unit 5 Electricity And Magnetism

Question 1

The 4 scientists and their discoveries

Answer 1

Oersted:
When a charge moves through a straight conductor a circular magnetic field is created
Ampere:
Solenoids create a magnetic field similar to a bar magnet
Faraday:
A current carrying conductor that cuts across external magnetic field lines experiences a force perpendicular to both magnetic field and the direction of electric current
Lenz:
If a magnetic field induces a current in a coil, the electric current is in a direction that it’s magnetic field opposed the change it produced

Question 2

Transformer equation

Answer 2

Vp/vs = Is/Ip = Np/Ns

Question 3

Power in a electrical circuit equation

Answer 3

P= vI
P=I^2R

Question 4

V=e/Q

Question 5

How do subwoofers work

Answer 5

Subwoofers use a solenoid surrounded by a magnetic. When there is a current in the coil it produces a magnetic field that attracts and repels to the magnetic. This vibrates a cone that produces sound waves

Question 6

How do electric bells work

Answer 6

There are two coils which produce a magnetic field when the switch is closed. There is an armature that is attracted to the magnetic field and rings the bell. At the same time this opens the circuit which causes the armature to spring back to its original position closing the circuit and continuing in a loop that rings a bell

Question 7

Electric difference equation

Answer 7

V= E/Q
I = Q/t

Question 8

How to increase strength of a magnet

Answer 8

Increasing number of loops
Increasing current
Introducing core material