A lens of focal length 15 cm is dippend in water

IIT JEE Discussion Forum › Optics questions › A lens of focal length 15 cm is dippend in water

A lens of focal length 15 cm is dipped in water. What is the new focal length given that ref index of glass wrt air is 3/2 and that of water wrt air is 4/3.
If the lens is dipped in a liquid under what condition, the rays
are not deviated.

#Physics #Optics

UP 0 DOWN 0 0 5
Post on FacebookPost anonymously?

5 Answers

Gaurav ·2010-02-11 05:22:48

Re:

UP 0 DOWN 0
Post on FacebookPost anonymously?

Manmay kumar Mohanty ·2010-02-11 05:36:22

Is the ans. 58.59 cm.

UP 0 DOWN 0
Post on FacebookPost anonymously?

Gaurav ·2010-02-11 08:26:45

i don't know the answer yaar.. please tell how u calculated??

UP 0 DOWN 0
Post on FacebookPost anonymously?

soumyadeep sanyal ·2010-02-11 09:07:32

the ans is 60 cm.
ref index of glass wrt water is (3/2)/(4/3)=9/8
now use lens makers formula...r1,r2 being the same in both cases would cancel.
f2/f1=(Î¼1-1)/(Î¼2-1)
f2=focal length in water.
Î¼1=3/2
Î¼2=9/8
f1=15

UP 0 DOWN 0
Post on FacebookPost anonymously?

Manmay kumar Mohanty ·2010-02-14 05:41:20

1f₁ = (32 - 1) [1R₁ - 1R₂] .........(1)

1f₂ = (3/24/3 - 1) [1R₁ - 1R₂] .........(2)

Dividing (1) by (2),
f₂f₁ = 0.50.128

f₂ = 0.5 x 150.128

f₂ = 7.50.128 = 58.59 cm.
Is it correct.

UP 0 DOWN 0
Post on FacebookPost anonymously?

Your Answer

Basic Integral Calculus Operators Symbols Matrix Cases

√ √ || {} [] () → ~ ^ x x x → → ln log lg lim lim cos sin tan cot arcsin arccos arctan

∫ ∫ ∫ ∫ ∫ ∬ ∬ ∬ ∬ ∬ ∭ ∭ ∭ ∭ ∭ ⨌ ⨌ ⨌ ⨌ ⨌

∑ ∑ ∑ ∑ ∑ ∮ ∮ ∮ ∮ ∮ ∏ ∏ ∏ ∏ ∏ ∐ ∐ ∐ ∐ ∐

+ - × ÷ ± ∓ = ∪ ∩ ≠ ∼ ≈ ∅ ∀ ∃ ∈ ∋ ∝ ≤ ≥ ≃ ≅ ≡ < > ≪ ≫ ⊂ ∉ ⊃ ⊆ ⊇ ⇒ ⇐ ⇔ ⇒ ⇐ ⇔ ⇑ ⇓ ⇕ → ← ↔ → ← ↔ ↑ ↓ ↕ ↖ ↗ ↘ ↙ ↪ ↩ ⇀ ↼ ⇁ ↽

° ∂ ∞ α β γ δ θ λ μ ν ξ π ρ σ φ ω ε ƒ κ τ υ Γ Δ Λ Σ Π Ω

Close [X]

A lens of focal length 15 cm is dippend in water

5 Answers

Your Answer

Add Image

Similar Questions