Download Magnetic Forces Practice

Magnetic Forces
Magnetic Field:
SI Unit:
1Tesla (T) = 1N/Am
Direction of Current
Smaller magnetic
force on current
carrying wire into
the page
Direction of Current
Small angle
Direction of Magnetic Field.
(shown lines of magnetic force)
Largest magnetic
force on current
carrying wire into
the page
900
Direction of Magnetic Field.
(shown lines of magnetic force)
Note: Unlike gravitational force or electric force, magnetic force is perpendicular
to the plane formed by the field and the moving charge, and is greatest when
the magnetic field and current are perpendicular to each other. The force on
the current carrying wire shown above is therefore into the plane of the page and
is determined by using the left-hand finger rule.
. 1 G = 1 x 10-4 T
Another unit for magnetic field is
The magnetic field at the surface of the earth is about 0.5 G or 0.5 x 10 -4 T
Strong electromagnets can produce fields on the order of 2 T and
superconducting magnets over 10 T
Magnetic Field can also be defined as
Lines moving
through unit surface
area perpendicular
to the field
B = Number of Magnetic Field Lines
Area perpendicular to field
=
Flux
Area
=
/A
1 Wb = 1 T m2
Flux is measured in
Example
A synchrotron accelerates protons and uses a steering magnet to bend them into
a curved path. Label the direction of the field on the diagram below which will
cause the bend the beam downwards.
+
F
v
Magnetic Forces Practice
1. Find the direction of the magnetic force on the charges below
X
+

_
v
v
_
B
v
2. Find the direction of B for each case below.
F
+
X
v
+
v
v
X
F
_
F
3. What is the direction of the magnetic field at the position of the compass
created by the wire?
4. What is the direction of the magnetic field at the position of the compass
created by the coil?
5. What is the direction of the magnetic force acting on the wire as a result
of the presence of the magnet?
6. Determine the direction of the magnetic force acting on wire number 1
7. Determine the direction of the magnetic field that will cause a beam of
electrons to move in a counterclockwise circular path shown below.
8. Describe the direction of the magnetic force acting on the wire as a result of
the magnetic field produced by the coil?
9. The end view of a coil of wire is shown. What is the direction of current flow
in the coil that will create a magnetic field B directed in the plane of the page?