Question

a covex mirror has a focal length 10 cm in air . if this mirror is kept in water ,its new focal length will be ( refracted index of water =1.33​

Answer 1

Answer:

PLZ MAKE AS BRAINLIEST

Explanation:

n is refractive index then

1/f=(n-1)(1/R’-1/R”)

let 1/R’-1/R”)=k.

then 1/fa=[n(ag) -1] k

if n(ag) = 3/2, n(Aw) =4/3

then n(wg) =n(ag) /n(aw)

=(3/2)*(3/4)=9/8

if fa=10cm

here fa is focal length of glass lens in air and

fw is focal length of glass lens in water then

1/fw=[n(wg)-1]k

1/fw=(9/8-1)k and

1/10=(3/2-1)k

dividing

10/fw=(9/8-1)/(3/2-1)

=(1/8)/(1/2)

10/fw=1/4

fw=10*4

fw=40cm. Answer