A. Charged Particles
A moving charged particle creates a magnetic field vector at every point in space
except at its position.
Symbol for Magnetic Field
B
mks units
[Tesla = T = N/(Am)]
other common unit
[Gauss = G] [1 G = 10-4 T]
This magnetic field exer
Application 1: Synchrotron (Particle Accelerator)
Accelerate charge particles with an electric force as they travel a circular path with
a fixed radius r. The magnetic field necessary to keep them moving in that circle is
found from the above force equati
AC Generators
A generator consists of a coil that is rotated in a magnetic field. A time-varying
voltage difference that regularly changes polarity is produced of the form
VM = amplitude of the voltage [V]
= angular frequency of the rotation [rad/s]
Note
Biot-Savart Law
A moving charge produces a magnetic field at a point P given by
A. Straight Wire
Field at a point due to the current in a straight wire segment
Size:
Direction: Field Right Hand Rule #1 (Field RHR #1)
1. Place thumb along current I so that
Faraday's Law
The magnetic flux through a loop of wire is
B = magnetic field penetrating loop [T]
A = area of loop [m2]
= angle between field vector and a vector perpendicular to the plane
of the loop
mks units of flux
[T-m2 = Weber = Wb]
If we define th
1
D. Solenoid (Coil)
Field at a point on the central axis of a solenoid with length and N turns
Size:
Direction: Field Right Hand Rule #2 (Field RHR #2)
1. Follow I around coil with fingers.
2. Thumb gives direction of B along axis.
Special Case: Long sol
Wave a disturbance in a medium that propagates
Transverse wave - the disturbance is perpendicular to the propagation
direction
(e.g., wave on a string)
Longitudinal wave the disturbance is parallel to the propagation direction
(e.g., sound wave)
1-D Wave
Converting from sound level to intensity:
= sound level [decibel = dB]
I = intensity in [W/m2]
Some sources of sound can be approximated as point sources. A point source
sends out a wave uniformly in all directions. The energy is spread out uniformly
acr
T = period = time for one oscillation or cycle [s]
f = 1 / T = frequency = number of cycles per time [cycles/s =
Hz]
= 2 / T = 2f
[rad/s]
The sign between kx and t determines the direction the wave travels along the xaxis.
+ wave travels to left (in the d
A inductor is a device that develops a voltage difference between the ends of the
device when the current (I) through it changes. The inductance (L) of the inductor
determines the size of the induced voltage (V).
If the time interval approaches zero, then