Electrophysics questions

Question 1

To test whether 2 magnets are permenant

Answer 1

• place the poles together (and repeat by rotating the first magnet to face its other pole towards the second magnet)
• repulsion (in one orientation and attraction in the other)

Question 2

TO make an electromagnet

Answer 2

• a coil of wire
• with an iron rod inside
• make sure coil is connected to a power supply

Question 3

how to change the strength of the magnetic field

Answer 3

• change the number of turns in the coil
• increase the current in the coil

Question 4

Describe the action of a relay

Answer 4

• the switch in the primary circuit is closed
• current in the coil creates an electromagnet
• the magnet attracts the armature
• armature pivots, closing the contacts
• the secondary circuit is completed

Question 5

Why is iron used as an electromagnet

Answer 5

because its a soft magnet, it only becomes temporily magnetic

Question 6

how to make a dc motor rotate faster

Answer 6

• increase the number of turns on the coil
• increase the current in the coil
• increase the strength of the magnetic fields

Question 7

Total internal reflection

Answer 7

• when light travels from a more dense medium to a less dense medium
• all light is reflected
• the angle of incidence is greater than the critical angle