Question

prove that 1/v-1/4=1/f in convex lens​

Answer 1

Explanation:

IS THE QUESTION CORRECT

?????~~~~~~~~~=≈

Answer 2

Correct question is 1/v -1/u =1/f

proved, 1/v -1/u =1/f

Proof :

Assumptions

1) lens is considered to be very thin with small apperture

2) object is considered to be point object.

Step 1 For refraction at AP1B

u1 = us , u2 = uL , R = +CC1 , U = -CO

V = Ci1

so,

uL/Ci1 + us/CO = (uL-us)/CC1

_____________(1)

Step 2 For refraction at AP2B

u1 = uL , u2 = us , R = -CC2 , U= -CC1

V = Ci2

so,

us/Ci2 + uL/Ci1 = (uL-us)/CC2

_____________(2)

Add (1)&(2)

us/CO + us/Ci2 = (uL - us)[ 1/CC1 +

1/CC2)]

For complete Lens

CO = -U , Ci2 = +V , CC1 = +R1 ,

CC1 = -R2

1/V - 1/U = (uL/us -1)(1/R1 - 1/R2)

Now if u = infinity then v = f

1/f = (uL/us -1)(1/R1 - 1/R2)

Hence, 1/V - 1/U = 1/f