Optics, fast help needed

  • Thread starter Saturnfirefly
  • Start date
  • Tags
    Optics
In summary: To find the object distance, you can use the magnification formula (m = -image distance/object distance) and plug in the given values (focal length = 20 cm, magnification = 4). Rearrange the equation to solve for the object distance, which should be -5 cm.
  • #1
Saturnfirefly
11
0

Homework Statement


1. When light travels from a material to air, total reflection occurs beyond 54 degrees. Calculate the index of refraction.

2. A converging lens has a focal length of 20 cm. When an object is placed at a certain disctance from the lens, a virtual image is created. How far from the lens is the object placed if the height of the image is 4 times greater than the object?

Homework Equations


1. sinC= n2/n1

2. ?

The Attempt at a Solution


1. I can use the equation, but I don't know how to calculate(?) the critical angle. I don't think any calculating is neccesary. The critical angle should be 45 (I'm not totaly sure) degrees, and my question is why?

2. I know that you have to place the object within the focal point to get a virtual image using a converging lens. And that tells us that the answer should be -something. But I don't know how to solve the equation... anyone that can by detail show me how to solve it? Answer should be di = -60
 
Last edited:
Physics news on Phys.org
  • #2
1) The critical angle is given. Use it to solve for the index of refraction.
2) If the image is 4x bigger than the object, what does that tell you about the ratio of object and image distances? (Look up magnification.)
 
  • #3
the critical angle is 54 degrees, not 45, or am i missing something here?

use the formula for the critical angle to calculate the index of refraction(sin critical angle = 1/refraction index)
 
Last edited:

1. What is optics?

Optics is the branch of physics that studies the behavior and properties of light, including its interactions with matter and the instruments used to detect and manipulate it.

2. How does optics relate to everyday life?

Optics plays a crucial role in many aspects of our daily lives, including vision, photography, telecommunications, and medical imaging. It also has applications in industries such as manufacturing, aerospace, and defense.

3. What are the main principles of optics?

The main principles of optics include reflection, refraction, diffraction, interference, and polarization. These principles govern how light behaves when it interacts with different materials and structures.

4. How is optics used in scientific research?

Optics is used in a wide range of scientific research, from studying the properties of materials to exploring the universe. It is used in various fields such as astronomy, biology, chemistry, and engineering to gather data and make observations about the natural world.

5. What are some common applications of optics in technology?

Optics is an essential part of many technological devices and systems, including microscopes, telescopes, cameras, lasers, and fiber optics. It is also used in the development of advanced technologies such as virtual and augmented reality, autonomous vehicles, and quantum computing.

Similar threads

  • Introductory Physics Homework Help
Replies
3
Views
320
  • Introductory Physics Homework Help
Replies
1
Views
903
  • Introductory Physics Homework Help
Replies
5
Views
966
  • Introductory Physics Homework Help
Replies
3
Views
800
  • Introductory Physics Homework Help
Replies
1
Views
1K
  • Introductory Physics Homework Help
Replies
10
Views
986
  • Introductory Physics Homework Help
Replies
3
Views
1K
  • Introductory Physics Homework Help
Replies
9
Views
825
  • Introductory Physics Homework Help
Replies
3
Views
2K
  • Introductory Physics Homework Help
Replies
12
Views
2K
Back
Top