"in a young’s double-slit experiment, the separation between slits is d and the screen is a distance d from the slits. d is much greater than d and λ is the wavelength of the light. the number of bright fringes per unit width on the screen is: "
a. dd/λ
b. dλ/d
c. d/dλ
d. λ/dd
e. d/dλ"

The number of bright fringes per unit width on the screen is,      

Explanation:

If d is the separation between slits, D is the distance between the slit and the screen and is the wavelength of the light. Let x is the  number of bright fringes per unit width on the screen is given by :

is the wavelength

n is the order

If n = 1,

So, the the number of bright fringes per unit width on the screen is . Hence, the correct option is (B).

a.   mass number from atomic number

the skeletons of most mammals reach a certain size and then stop growing. however, many animals, including some mammals, keep growing throughout their lives. kangaroos, for example, just keep growing and growing until they die. also, the longer an animal lives the greater the chance it might catch some deadly disease.