Investigate, using a search coil and oscilloscope, the effect on magnetic flux density of varying the angle between a search coil and magnetic field direction

Question 1

What is a search coil?

Answer 1

• small flat coil a made from 500 - 2000 turns of insulated wire mounted on a handle

Question 2

How is an emf induced in the coil?

Answer 2

• placed inside a varying magnetic field

Question 3

How does the flux through the coil constantly change?

Answer 3

• connected to alternating power supply

Question 4

Why is it connected to an oscilliscope?

Answer 4

• record the induced emf

Question 5

What happens wghen the field is varying at a constant rate?

Answer 5

• the amplitude of the induced emf will be directly proportional to the amplitude of the magnetic flux density of the field

Question 6

How is the equipment set up?

Answer 6

• search coil clamped with its face perpendicular to the flux lines produiced by the circular coil
  
  • θ = 0
• as cos0 = 1
  
  • max flux linkage and max induced emf in search coil

Question 7

Why is the time base of the oscilloscope switched off>

Answer 7

• induced emf displayed as vertical line
• measurement taken of this line

Question 8

How is amplitude calculated from the length of line

Answer 8

• half the length of the line
• and by referring to the y-gain setting on the oscilliscope

Question 9

How is the experiment done from there?

Answer 9

• coil rotated and induced emf measured at each angle
  
  • 10 degrees each time
  • emf will decrease
• measure angle using potractor

Question 10

What is the safety concern in this experiment?>

Answer 10

• coil taking relatively large current, it will heat up
• do not leave on for longer than necessary

Question 11

why does emf decreaSE?

Answer 11

• the search coil is cutting fewer flux l;ines as the component of the magnetic field perpendicular is lower
• this means that the magnetic flux linkage is lower