Help me with this question. (It to was WAY to looooong so I put it in the desciption.

Question

The wavelength of an X-ray is 1 nano meter, or 10^-9 m. X-rays travel at the speed of light, which is 3 X 10⁸ meters per second. The frequency of a wave (cycles per second) is equal to the speed of the wave (in meters per second) divided by its wavelength (in meters). What is the frequency of the X-ray.

 

Write the answer in scientific notation.

Answer 1

The frequency of a wave (cycles per second) is equal to the speed of the wave (in meters per second) divided by its wavelength (in meters).  Let f be frequency, s be speed, w be wavelength, using meters and seconds as the basic units.

 

f = s/w

f = 3•10^{8 ÷} (10^-9) = 3•10¹⁷ Hz ("cycles per second")

Answer 2

freq = speed / wavelength

 

plug in and crunch the numbers:  (3 x 10⁸ m/s) / (1 x 10^-9 m),

make sure your calculator is in scientific notation an you will get the answer 3 x 10¹⁷ or 3E17

 

if you are not getting the correct exponent, check how you are entering exponents in your calculator.  If you are using 10^power, you will need to be careful in your entry.  If you entered 3 x 10^8 / 1 x10^-9, you will get an answer of 0.3.  Your calculator will process the calculation as

3 x 10⁸ x 10^-9 / 1.  Best and most straight forward method to the calculation is to use the EE or exp function.  The calculator recognizes 3EE8 / 1EE-9 as (3 x 108 m/s) / (1 x 10-9 m).