__
Objective:__

The objective of this experiment is to measure the period of rotation and angular speed of a moving charged-particle in a magnetic field

__Equipment:__

A computer with internet connection, a calculator (The built-in calculator of the computer may be used.), paper, and pencil

__
Theory:__

When a charge q** **of mass** **
M** **moving at a velocity
**v**
crosses a magnetic field B* *perpendicular to its
field lines, the magnetic field forces the charge to travel along a circular
path of radius R given by

Cross multiplying yields: RqB = Mv. This may be written as:

(1)

In this formula, w is
the angular speed (rad / s) of the rotating charge, q**/**M
is the charge-to-mass ratio (Coul. / kg), and B is the
strength of the magnetic field in Tesla.

__Procedure:__

click on the following link** : **
http://www.phy.ntnu.edu.tw/ntnujava/index.php?topic=36.0

You should see a 3-D figure. The magnetic field
B is upward shown by a blue vector along the Positive
Y-axis. The electric field **E** is shown by a red vector along the
positive X-axis. In each case of this experiment, we will set the electric
field components equal to zero because we are studying the motion of a charged
particle in a magnetic filed only**.** Above the coordinates system,
spaces are provided to type in the desired values for E_{x},
E_{y}, and E_{z}.
Before setting them equal to zero, the drift velocity, **V _{i}**,
or

For each case of the following Table**:**

1) Adjust the value of **V**_{d}
or **V _{i}** as given in the Table by the left
click held down as was explained,

2) select a value for q/M and one for B and type them in,

2) set E_{x} = 0**,**
( E_{y}, and
E_{z} are already zero),

3) click start. You will see the time running.

If you measure the time t of n rotations and then divide it by n, you will find the period of rotation, T.

4) since w = 2p/T, divide 2p by T to find w.

5) This value of w
is your measured value. It must be very close or equal to the accepted
value that you calculate from Formula (1) above**.**

6) Calculate a %error for each case**.**

Note: **To completely reset the
applet for each new case, you must click on refresh and refresh the screen.**

__Data: __

__Given: __

** **

Trial | V_{d}m/s |
B Tesla |
q / M Coul/kg |
t sec. |
n turns |
T = t / n |
Accepted w = (q /M)B |
Measured w = 2p/T |
% error |

1 | 20.0 | 50.0 | 0.01 | ||||||

2 | 30.0 | 40.0 | 0.025 | ||||||

3 | 35.0 | 80.0 | 0.025 | ||||||

4 | 40.0 | 80.0 | 0.050 | ||||||

5 | 50.0 | 90.0 | 0.060 |

__Measured:__

** ** Values
of w to be recorded in the above Table.

__Calculations:__

Follow the steps under "Procedure."

__
__

__Comparison of the
Results:__

The accepted and measured values of M may be used to obtain a percent error:

__Conclusion:__
To be explained by students

__Discussion:__
To be explained by students