How does current create a magnetic field?

Question 1

What happens when a current flows through a wire? How can we increase this effect?

Answer 1

A circular magnetic field is produced around it.

The strength of the m.f. produced is greater:

• closer to the wire
• if the current is increased.

Question 2

Describe the Right Hand THub Rule.

Answer 2

1. Thumb points in the direction of the current.

2. The curve of the fingers shows the direction of the magnetic field produced.

Question 3

Describe and explain Fleming’s Left Hand Rule.

Answer 3

1. The thumb points in the direction of the force.
2. The index finger points in the direction of the m.f.
3. The middle finger points in the direction of the current,
4. Fleming’s Left Hand Rule states that a current-carrying wire experiences a force that acts perpendicular to the magnetic field produced by magnets.

Question 4

What is the strength of the force exerted in Flem. LHR proportional to?

Answer 4

1. The strength of the m.f.
2. The current.
3. The no. of turns on the coil.

Question 5

How would we reverse the direction of the force in Flem. LHR?

Answer 5

• Switch the magnets around (Reverse the direction of the m.f.)
• . Reverse the direction of the current flowing through the wire

Question 6

How do we calculate the force in Flem. LHR?

Answer 6

Force (Newtons) = Magnetic field strength (B,Teslas) * Current (I,Amps) * Length of wire (Metres)