Index of refraction for converging lens

Click For Summary
A thin converging lens with radii of curvature R1=9cm and R2=-11cm has a focal length of 5cm. Using the Lens Maker's equation, the initial calculation for the index of refraction yielded n2=10.9, which was incorrect. The error was due to not accounting for the negative value of R2. After correcting this mistake, the accurate refractive index was determined to be 1.99. This highlights the importance of correctly applying sign conventions in optical calculations.
vetgirl1990
Messages
85
Reaction score
3

Homework Statement


A thin converging lens has radii of curvature of R1=9cm and R2=-11cm. Assume its focal points F1 and F2 are 5cm from the center of the lens. Determine its index of refraction.

Homework Equations


Len's Makers equation: 1/f = (n2 - n1 / n1) (1/R1 - 1/R2)

The Attempt at a Solution


focal length f = 5cm
n1 = air = 1

Plugging in all my known values:
1/5 = (n2 - 1) (1/9 - 1/11)
n2 = 10.9

This value for refractive index doesn't make sense at all... so I'm not sure what I'm doing wrong!
 
Physics news on Phys.org
Did you take into account that R2 is negative?
 
  • Like
Likes vetgirl1990
TSny said:
Did you take into account that R2 is negative?
D'oh! What a ridiculous mistake. Yes, with that taken into account the refractive index is 1.99.
 
OK, good.
 

Thread 'Magnitude of buoyant force in fluids of different densities'

The book claims the answer is that all the magnitudes are the same because "the gravitational force on the penguin is the same". I'm having trouble understanding this. I thought the buoyant force was equal to the weight of the fluid displaced. Weight depends on mass which depends on density. Therefore, due to the differing densities the buoyant force will be different in each case? Is this incorrect?
View full post »

Similar threads

Lens with different refraction index on each side
  • · Replies 7 ·
Replies
7
Views
2K
Calculate the focal distance of the duplicate
  • · Replies 3 ·
Replies
3
Views
1K
Lens-Makers Equation: Finding Focal Length in Different Mediums
  • · Replies 2 ·
Replies
2
Views
3K
Find the refractive index for the lens and find the image distance
  • · Replies 3 ·
Replies
3
Views
2K
Optics: refraction and reflection
  • · Replies 1 ·
Replies
1
Views
2K
Image distance from the hemisphere lens
  • · Replies 9 ·
Replies
9
Views
2K
Analyzing this 2-lens optical system
  • · Replies 5 ·
Replies
5
Views
2K
How would you calculate the refractive index?
  • · Replies 1 ·
Replies
1
Views
2K
Undergrad Sine laws of spherical singlets
  • · Replies 72 ·
3
Replies
72
Views
6K
What Condition Ensures Refracted and Incident Rays Have the Same Direction?
  • · Replies 4 ·
Replies
4
Views
2K