Physics

Question 1

How does an MRI work?

Answer 1

• Water inside body is magnetic due to hydrogen particles
• MRI machines use strong magnets to create a magnetic field around the body
• Magnetic field aligns these particles in the body
• Then they send radio waves which makes the particles absorb energy
  *When the radio waves stop, the particles release this energy as signals
• Machine detects signals and turns them into pictures

Question 2

Electromagnetic induction

Answer 2

when a changing magnetic field creates electricity in nearby objects

Question 3

How does a metal detector work?

Answer 3

• a coil creates a changing magnetic field
• When field passes over metal, it makes an electric current in the metal
• Current makes magnetic field
• Metal detectors pick up this magnetic field to find the metal

Question 4

How do induction chargers work?

Answer 4

• both the charger and the device have to have wire coils inside
• when device is placed on the charger it makes an electric current in the coil inside the device
• this current charges the devices internal battery

Question 5

Step down transformers

Answer 5

fewer windings in secondary coil therefore decreased voltage

Question 6

Step up transformers

Answer 6

more windings on secondary coil therefore increased voltage

Question 7

AC generators

Answer 7

• covert mechanical energy into electrical energy
• AC has slip ring, DC does not

Question 8

How does a bell work?

Answer 8

• a magnet attracts a clapper when powered
• the clapper hits the bell, makes sound
• when power stops, sound ends

Question 9

How does a speaker work?

Answer 9

• electricity flows through a coil in the speaker
• the coil interacts with a magnet, making a diaphragm move
  *moving diaphragm creates sound waves