Optics Problems: Concave Mirrors and Refraction Calculations

  • Thread starter Prime
  • Start date
An interesting problem. I am not sure how to go about this, but I will give you some of my thoughts.(1) I am a little confused by the wording of the problem. Is the object always 30 cm in front of the mirror? If so, then the problem seems to be saying that the radius of curvature of the mirror is 15 cm. Since a concave mirror has a focal length of half its radius of curvature, it would seem that this mirror has a focal length of 7.5 cm.(2) I am also a little confused by the wording of the problem when it says "a)find the position and size of the
  • #1
Prime
HElp ME PLEASE

Hello my name is Scott Johnson I was just wondering if u could help me with thse two problems I am stuck on. I have I deadline for tommorrow so if u could email me back today that would be great.greatlt apprecated

1) a 0.50 cm high object is placed 30 cm in front of a concave mirror that has a 15cm radius of curvature. a)find the position and size of the image and state whether it is real or virtual and upright or inverted. Repeat the distances of b) 15 cm, c) 12 cm, and d) 6 cm. check your calculations with ray diagrams. (20 pts for each letter section)

2)Light at an incident ray of 37degrees enters a flat glass plate (n=1.50). a)what is the angle of refraction inside the glass? b) after the beam leaves the plate, what is the angle between it and the beam incident on the plate? (10 pts for each letter section)
 
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  • #2
Prime,

Forum rules state that for us to help you, you need to show your work and where you got stuck.

It does absolutely nothing for you if someone gives you the answer, and is considered cheating if the problem is graded.

So post what you've tried, and we'll help you out.
 
  • #3
its not graded.

if u place a .50cm high object in frount of a 30 concave mirrior the curauture of it woul dbe 15 cm in radios

so would this mean that because the distance form the mirroir is cut in half the equals the radious. And would u do that for all of them

most of it makes no sense to me, my teacher gave me this question to see if we were deciated to our work..any sorce made be used in these questions that's why i posted it
 
  • #4
its not graded.

if a .50 cm high object is placed 30 cm in front of a concave mirrior that has 15 cm radious curature.

does this mean that the distance between the mirrior and the object its cut in half to equal the radious?

this is not graded it is just a problem that our teacher has given us to see if were deciated to our work. Any sorces our availbe for uses. Thats why i posted it please help me. Please
 
  • #5
this is the problem i can't understand this

Hello my name is Scott Johnson I was just wondering if u could help me with thse two problems I am stuck on. I have I deadline for tommorrow so if u could email me back today that would be great.greatlt apprecated

1) a 0.50 cm high object is placed 30 cm in front of a concave mirror that has a 15cm radius of curvature. a)find the position and size of the image and state whether it is real or virtual and upright or inverted. Repeat the distances of b) 15 cm, c) 12 cm, and d) 6 cm. check your calculations with ray diagrams. (20 pts for each letter section)

2)Light at an incident ray of 37degrees enters a flat glass plate (n=1.50). a)what is the angle of refraction inside the glass? b) after the beam leaves the plate, what is the angle between it and the beam incident on the plate? (10 pts for each letter section)
 
  • #6
For question 1a, draw a concave mirror and an object on your graph paper. You should apply the laws of reflection in this case. Light rays from the object parallel to the principle axis will pass through the focus, and vice versa. Repeat the above steps to do part b, c and d. When will the image be real/virtual ?
Here is a link for your reference.

For question 2, I think you have learned a formula relating angle of incidence, angle of refraction and refractive index, right? Try to apply that formula.
 
Last edited:
  • #7
more

can u give me a little more info
 
  • #8
Start with 1. recalling thin lens (thin mirror) equation and 2. relationship between radius of curvature and focal length for a mirror.
 
  • #9
Yeah, this is prolly too late, but some equations to get you started:

f=r/2 where r is the radius of curvature..

and

1/di + 1/do=f
Keeping in mind that the focal distance is negative for diverging instruments and positive for converging ones.
 
  • #10
Prime,

Welcome to Physics Forums.

I merged your two threads together into a single thread. In the future,

1. In the Homework Help forum, please show us some of your work.
2. Please start only one thread per problem.

Thanks,
 

1. What is the difference between a concave and convex mirror?

A concave mirror curves inward and can reflect light to a focal point, while a convex mirror curves outward and reflects light outward.

2. How do you calculate the focal length of a concave mirror?

The focal length of a concave mirror can be calculated using the formula: f = R/2, where R is the radius of curvature of the mirror.

3. How does the position of an object affect the image formed by a concave mirror?

The position of an object in front of a concave mirror affects the image formed by determining the size, orientation, and location of the image. An object placed beyond the focal point of the mirror will produce a real, inverted, and diminished image, while an object placed between the focal point and the mirror will produce a virtual, upright, and magnified image.

4. What is refraction and how does it affect the path of light?

Refraction is the bending of light as it passes through different mediums with varying densities. It is responsible for the change in direction and speed of light as it moves from one medium to another. The amount of refraction depends on the angle at which the light enters the medium and the difference in density between the two mediums.

5. Can you use the same calculations for refraction in different mediums?

No, the calculations for refraction will differ depending on the properties of the mediums involved, such as their densities and indices of refraction. Each medium has its own unique characteristics that must be taken into account when calculating the refraction of light passing through it.

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