應用光學 Homework 1
1.
The wavefunction of a transverse wave on a string is
 ( x, t )  (30.0cm) cos[(6.28rad / m) x  (20.0rad / s)t ].
Compute the (a) frequency, (b) wavelength, (c) period, (d) amplitude, (e) phase
velocity, and (f) direction of motion.
2. Draw the wavefront of the following uniform plane waves:
(a)  ( x, t )  cos(x  t )

(b)  (r , t )  cos(x  y  t )
3.
An electromagnetic wave in a dielectric medium is specified by the following
function:
 
1
E (r , t )  (6iˆ  3 5 ˆj )(10 4 V / m) exp{i[ ( 5 x  2 y )  10 7  9.42  1015 t ]}
3
Find (a) the direction along which the electric field oscillates, (b) the amplitude E0
of
4.

E , (c) propagation number and wavelength, (d) the speed.
A light bulb puts out 20W of radiant energy (most of it IR). Assume it to be a
point source and calculate the irradiance of 1.00m away.