Directional Indicators

1
Directional Indicators

• Arrows represent direction, but so do Xs and
  Os.
• A current or field line which points into the
  plane of the board is indicated by the symbol X
• A current or field line which points out of the
  plane of the board is indicated by the symbol O
• A current or field which forms a circle may be
  indicated by a directional arrow, which is not
  a true vector.
• Xs N Os would make a neat license plate,
  too.

2
The 1st Right Hand Rule

• The thumb represents the direction of the current
  flow.
• The fingers curl in the direction of the magnetic
  field.

3
Finding the Direction of the Magnetic Field Using
the 1st Right Hand Rule

• Draw the direction of the magnetic fields
  resulting from the current carrying wire shown.

X
O
4

• The direction of the magnetic fields resulting
  from the current carrying wire shown.

X
O
5

• Draw the direction of the magnetic field which
  would be found above and below the wire shown.

I is to the right
6

O O O O O O
X X X X X X
I is to the right
7
Find the direction of the magnetic field due to
the current in the wire ring (solenoid).
8
The direction of the magnetic field is due to the
current in the wire ring (solenoid).
X X
9
2nd R.H.R.

• Fingers indicate the direction of the magnetic
  field (no curling of the fingers)
• Thumb indicates the direction of the current
  flow
• Palm indicates the direction of the force on
  the current carrying wire.

10
Find the direction of the force on the current
carrying wire in the situation below.
Current
Magnetic Field
11
The direction of the force on the current
carrying wire in the situation below is ...
Current
Force
O
Magnetic Field
12
Find the direction of the force on the current
carrying wire for the situation below.