Magnetic fields part 2

Question 1

What happens if you put a current-carrying wire into an external magnetic field (e.g. between two magnets)

Answer 1

• the field around the wire and the field from the magnets are added together
• this causes a resultant field
• lines closer together show where the magnetic field is strong
• these bunched lines cause a pushing force on the wire

Question 2

What is the direction of the force in a wire carrying a current in a amagentic field?

Answer 2

• always perpendicular to both the current direction and the magnetic field
• given by Fleming’s left hand rule

Question 3

What happens in the current is parallel to the field lines?

Answer 3

• size of force is 0 N
• there is no component of the magnetic field perpendicular to the current

Question 4

What is Fleming’s Left-Hand Rule

Answer 4

Question 5

What is magnetic flux density?

Answer 5

• B
• force on a current-carrying wire at a right angle to an external magnetic field is proportional to B
• sometimes called the strength of the magnetic field
• defined as
  
  • the force one one metre of wire carrying a current of one amp at right angles to the magnetic field

Question 6

What is flux density?

Answer 6

• number of flux lines (Wb) per unit area
• vector quantity w/ direction and magnitude
• measured in teslas