# Magnetic Fields

## Physics – Electric Currents and Magnetic Fields

For the figure below how, large must the current be to produce a magnetic field of at a distance of 2 cm from a wire as shown? What is the direction of the field at this point?

#### Figure

#### Relevant Equation

#### Find

current and field direction

Solve the equation for “I”:

Plug in the numbers:

Finding the direction of the field: The right-hand rule.

- Point thumb of right hand in direction of the current. Keep palm flat and thumb extended at a right angle to other fingers.
- Leave thumb extended and fold fingers into palm.
- Observe that the magnetic field will follow your fingers (knuckle to fingertip).

Resulting field if current is coming out of page (like you are looking at the end of wire that current is coming out of)