Question

The wavelength of red helium–neon laser light in air is 632.8 nm. (a) What is its frequency? Hz (b) What is its wavelength in glass that has an index of refraction of 1.51? nm (c) What is its speed in the glass?

Answer 1

Step-by-step explanation:

It is given that,

The wavelength of red helium–neon laser light in air is,
`\lambda=632.8\ nm=632.8* 10^(-9)\ m`

(a) Frequency,
`f=(c)/(\lambda)`

`f=(3* 10^8\ m/s)/(632.8* 10^(-9)\ m)`

`f=4.74* 10^(14)\ Hz`

(b) Let
`\lambda_g` shows its wavelength in glass that has an index of refraction of 1.51,

`\lambda_g=(\lambda)/(n)`

`\lambda_g=(632.8* 10^(-9)\ m)/(1.51)`

`\lambda_g=4.19* 10^(-7)\ m`

`\lambda_g=419\ nm`

(c) Let
`v_g` is its speed in the glass.

`v_g=(c)/(n)`

`v_g=(3* 10^8\ m/s)/(1.51)`

`v_g=1.99* 10^8\ m/s`

Hence, this is the required solution.