physics 101

1. Light Interference
Physics 101
Samantha Sam

2.  Light interference when waves of the same frequency
superpose or interfere with each other to either
increase or decrease the amplitude
Definition
=+
Example of interference:

3. I = I1 + I2 + 2√(I1I2)cos(ΔΦ)
 I=resulting intensity
 I1 & I2= Intensities of the current waves interfering
 ΔΦ= phase difference
Formula

4.  If we have two identical waves:
 The phase difference between them are 0
 I1=I2
 I=2I1/2+2I1/2cos(0)=4I
 The resulting wave intensity is constructive and 4 times the
intensity of the original waves.
Formula
Wave 1 Wave 2

5.  If the phase difference between them is π then
 I1=I2
 I=2I1/2+2I1/2cos(π)=0
 The resulting wave is a destructive interference wave
and the intensities are cancelled out.
Formula

6.  If the 2 sine waves collide, one wave is a third of the
wave of the second wave, what is the total intensity
of the resulting wave?
Question

7.  I = I1 + I2 + 2√(I1I2)cos(ΔΦ)
 I1=(1/3)I2
 I2+(1/3)I2 +2√(I2+(1/3)I2) cos(0)=0
 The resulting intensity is 0.
Answer