# Wave and optics help

1. Jun 23, 2005

### GingerFish

hey guys i have two questions that i wouldn't mind some help on !

firstly
a wave in the form (in meters) of y = 0.5sin(4(pi)t+0.5(pi)x) where t and x are time and space co-ordinates in seconds and meters

find the wave length amplitude frequency and speed of the wave.
is the wave traveling in the +x or -x direction?

and

a hand glider is flying at an altitude of h=125m, green light of wavelength 555nm enters the pilots eye through a pupil that has a diameter D = 2.5mm. the average index of refraction of the material in the eye is n = 1.36.
Determine how far aprt two point objects must be on the ground if the pilot is to have any hope of distinguishing them.

any help will be great!

2. Jun 23, 2005

### Galileo

Hi Gingerfish.

I guess you could just look into your book and see how you can get the speed of the wave, the wavelength and so on.

I usually don't remember all these relations, but you can recover them easily from the formula.
To know the wavelength, imagine taking a snapshot of the wave at a certain instant and then measure the length of one complete period. That is the wavelength. So just put t=0, x=0 ($\sin(0)$)and see how far to the right you have to go to finish one complete revolution (at $\sin(2\pi)$).
You can do a similar thing for the period of revolution (which is easily related to the frequency).
I`m sure you can find the amplitude. If not, read your book.

3. Jun 23, 2005

### GingerFish

thanks

thanks man i'm working at it, but i don't have any of the course notes at the moment and they havn't been uploaded to the university web space yet

so i don't have any of the formula's handy and i don't know them off by heart

i wouldn't post if i could just look it up, i couldn'd fins anything helpful with google

i'm not lazy!