This document discusses solenoids and straight line conductors. It explains that a solenoid produces a magnetic field similar to a bar magnet when electric current flows through a coil of wire. The direction of the magnetic field can be determined using right hand and left hand rules. It also discusses that straight line conductors produce circular magnetic fields around the conductor, and the direction of the field is determined using right hand and left hand rules based on the conventional flow of electrons.

1. SOLENOIDS
Objectives:
2.3 Map the magnetic field around a
current bearing:
a) straight line conductor
b) solenoid

2. Solenoid
 Wire wrapped in a coil with a current
flowing
 Makes a magnetic field
 Their magnetic fields look like the
magnetic field around a bar magnet.

3. Cores
 A Core is the object that is inserted into
the solenoid, creating an electromagnet.
 Different materials influence the strength
of the electromagnet: Iron, Nickel or
Cobalt.
 Iron is most commonly used because
when you turn off the electricity it
demagnetizes.
 Steel is not used because it remains
magnetized thus creating a permanent
magnet.

4. Solenoid
 2 Methods
 Right Hand rule
 Left Hand rule
 Either Method works

5. Solenoid Rules – Right Hand Rule
 Step #1: Place palm of right hand on
positive end.
Finding
North & South
Poles
- +

6. Solenoid Rules – Right Hand Rule
 Step #2: At the positive end, look
to see if the wire is in front or
behind the middle tube.
Wire is in
Front of the core
At positive end.
+-

7.  Step # 3: If the wire is in front of
the tube at the positive end, place
your hand on top of the core.
Solenoid Rules – Right Hand Rule
- +

8.  Step # 4. If the wire is behind the
tube at the positive end, place your
hand under the tube.
Solenoid Rules – Right Hand Rule
- +
Palm Up
Hand under tube

9.  Double check both palm and
fingers.
 Step #5. Thumb points towards
North. The other end is South.
Solenoid Rules – Right Hand Rule
- +

10. Solenoid Examples - # 1
1. Go to the
positive
2. Wire runs behind
core
3. Hand goes under
core & fingers
curl up
4. Thumb points N.
Other end is S.
5. Lines of Magnetic
force run N
(Nerd) to S
(Sexy).
+-

11. Solenoid Example # 2
1. Find Positive
2. Wire runs in
front of core
3. Place hand on
positive
4. Thumb points
to North
5. Other end is S
6. Magnetic field
runs N (Nerd)
to S (Sexy).
-+

12. Activities
 Work Sheet Mod II, # 3
 Observatory, p. 174, Q. 25

13. Effects of Placing a Compass Near a
Solenoid
1. Label North and South.
2. Draw in arrow on compass.
Example #1
- +
Compass
Remember
That the
Needle is
North
Needle points
to
South

14. More Examples
1. Label North and
South.
2. Draw in arrow on
compass.
Example #2
-+
Compass

15. When Two Solenoids Meet
 Answer: Solenoids would attract.
Would they attract or repel?
+ -
- +
Likes
Repel &
Opposites
Attract

16. Solenoid without a + or -
In a battery
the longer line is
ALWAYS
positive
First
Find the
positive
+ -

17.  Right Hand Rule: Use only the right
hand to label N and S.
 Before solving a problem, always label
N and S first.
 Red Compass needle is North and
is attracted to South.
 When the + and the – are not given
on a diagram, remember that the
longer line on the battery is always
positive.

18.  Wires with electricity flowing through them
 Like solenoid have N and S poles and
magnetic field.
Straight Line Conductor

19.  Step # 1: Using your right hand,
point your thumb towards the
negative post
Straight Line Conductor
Right Hand Rule
- +
Hand on top
in this
situation

20.  Step # 2: With your hand open,
your kNuckles are North, and your
finger tipS are South.
Straight Line Conductor
Right Hand Rule
+-

21. Straight Line Conductor
Right Hand Rule
If your hand is
behind the wire,
curl your hand
around the
wire.
-+
-+
kNuckles are
up (N)
finger tipS are
down (S)

22. Placing N & S –
Straight Line Conductor
+
+
+
+
-
-
-
-

23. Effects of a Compass on a
Straight Line Conductor
- +
Compass arrow
Always points
South
Compass

24. Armour Rule:
 For a straight line conductor
connected to a source of electricity,
the finger tips of the right hand
point in the North direction of the
compass.

25. Straight Line Conductor
Examples
-
-
-
- +
+
+
+
A B
C D

26.  Right Hand Rule for Straight Line
Conductors – Thumb points to
negative
 North and South are never on the
ends of the line
 Remember that the compass needle
is North and is attracted to South
 kNuckles are North and finger tipS
are South.

27. Activity
 Worksheet Module 2, # 5
 Page 174, Q. 24

29. Important Symbols & Facts
 Magnetic field: represented by B.
 Current: represented by I.
 Magnetic Poles:
 North pole (N)
 South Pole: (S)
 Magnetic Field: Circular around a
straight line.

30. Solenoid Left Hand Rule
 Determine direction by the Left Hand rule
– fingers wrap in the direction of the
electron flow and thumb points in the
direction of the magnetic field (N).
e-

31. Straight Line Conductor
 Current (I):
 flow of electrically charged
particles through a
conductor
 Conventional Current
 Traditionally scientists believed that
current was positive.
I
+

32. Straight Line Conductor
Left Hand Rule
 According to the flow of
electrons, your thumb (left
hand) follows the direction
of the electrons.
 Fingers wrap around the
wire, giving the shape and
direction of the magnetic
field.
e-
B
e-
+-
JJ Thomson
Electricity produced by
electrons
Electron flow