Question

Light of wavelength 510 nm is used to illuminate normally two glass plates 24.3 cm in length that touch at one end and are separated at the other by a wire of radius 0.023 mm. How many bright fringes appear along the total length of the plates.

Answer 1

`m = 180 \ bright \ fringes`

Step-by-step explanation:

From the question we are told that

The wavelength is
`\lambda = 510 \ nm = 510 *10^(-9) \ m`

The length of the of the plate is
`l = 24.3 \ cm = 0.243 \ m`

The radius of the wire is
`r= 0.023 \ mm = 2.3 *10^(-5) \ m`

Generally the diameter of the wire which is the distance between the glass plates is mathematically represented as

`d = 2 * r`

=>
`d = 2 * 2.3 *10^(-5)`

=>
`d = 4.6 *10^(-5) \ m`

Generally the condition for constructive interference is mathematically represented as

`2 *d = m \lambda`

=>
`m = (2d)/(\lambda)`

=>
`m = (2 * (4.6* 10^(-5)))/( 510 *10^(-9) )`

=>
`m = 180 \ bright \ fringes`