What is Concave mirror: Definition and 88 Discussions

A curved mirror is a mirror with a curved reflecting surface. The surface may be either convex (bulging outward) or concave (recessed inward). Most curved mirrors have surfaces that are shaped like part of a sphere, but other shapes are sometimes used in optical devices. The most common non-spherical type are parabolic reflectors, found in optical devices such as reflecting telescopes that need to image distant objects, since spherical mirror systems, like spherical lenses, suffer from spherical aberration. Distorting mirrors are used for entertainment. They have convex and concave regions that produce deliberately distorted images. They also provide highly magnified or highly diminished (smaller) images when the object is placed at certain distances.

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  1. Z

    Paraxial approximation on concave mirror

    1. Find the length of the curvature of a concave mirror of 20cm that comply with paraxial approximation for all incident rays 2.conventional geometry formula , sinθ≈θ or tanθ≈θ for paraxial rays 3. I had try drafting out the diagram , labeling all the unknown angle with symbol and...
  2. L

    Sound reflection & controversy in ray diagram of concave mirror

    I've two questions here:- 1) Sound reflects it is said using laws of reflection of light.So,it means we hear max. sound when angle of incidence is equal to angle of reflection,right?& if not equal then what do we hear or not? I guess we hear lesser than max.sound when the angles are not equal...
  3. X

    Concave Mirror Experiment Question

    Homework Statement We did an experiment with a concave mirror. Concave mirror was placed on optics bench and a candle was placed at designated spots. A screen was used to see where the image was projected. When the object was placed between the focal point, image was not produced on the...
  4. L

    Quick and easy way to measure magnication of a concave mirror

    Hi, We're offered shaving mirrors by suppliers and sometimes their claims to the magnification are doubtful. I don't wish to upset any customers by giving incorrect information. So is there a practical way in which I can test the magnification myself? i.e. measuring the distance of the...
  5. J

    Position Object for Inverted, Magnified Image with Concave Mirror

    Where do you put an object in front of a concave mirror of focal length 10 cm to produce an image that is inverted and 2.5 times greater than the object? I have no idea how to solve this.. help..
  6. S

    Foca length of a concave mirror

    Homework Statement A concave mirror of focal length 10cm in air is put into a beaker containing a liquid up to 7.5cm. Refractive index of the liquid is 1.2. What is the focal length of the mirror inside the beaker? The Attempt at a Solution I tried proportion method: Depth...
  7. C

    Image Distance of a concave mirror ( with algebra)

    Homework Statement A concave mirror with a focal length of 34.4 cm produces an image whose distance from the mirror is one-third the object distance. Calculate the object distance. Homework Equations (1/f)=(1/do) + (1/di) The Attempt at a Solution I know that i have to use the...
  8. S

    Concave mirror equation calculation

    Homework Statement A physics student wants toobtain a real and virtual image that each is 3 times as large as the original object she has a concave mirror with a 0.50 m radius of curvature. what object distance will she require to obtain the real image? Homework Equations 1/do + 1/di =...
  9. I

    Calculating the Focal Length of a Concave Mirror

    concave mirror! Homework Statement The real image produced by a concave mirror is found to be 0.756 times the size of the object. If the distance from the mirror to the screen on which the image appears is 0.764 m , what is the focal length of the mirror? Homework Equations (a) 1...
  10. P

    Concave mirror - finding object and image distance

    Homework Statement A concave mirror has a focal length of 27.2 cm. The distance between an object and its image is 50.2 cm. Find (a) the object and (b) the image distance assuming that the object lies beyond the center of curvature. Homework Equations f=1/2 R 1/object distance + 1/image...
  11. A

    Exploring the Focal Point of a Concave Mirror

    I know that when the focal point is in the inside of a concave mirror. The focal point is greater than zero, and the radius is greater than zero and the lateral magnification is greater than zero. So if the focal point is on the outside of this concave mirror. Would the focal point be...
  12. A

    Stargazing Where should the secondary mirror be placed in a concave mirror telescope?

    hello, I found a concave mirror telescope in my town I think that it is very good for making Newton telescope Estimated length of 20 cm I will make a telescope , but I have a problem , I do not know the place of the focus and the place of secondery mirror; after focus or before...
  13. J

    Magnification for concave mirror

    A concave mirror creates an image on the screen 2x larger than the object. BOTH objects and screen are subsequently moved in order to create an image on the screen 3x larger than the object. If the screen is moved 0.75 m in this process, how far is the object also moved? --- Magnification, M =...
  14. I

    Concave mirror positioning help

    Homework Statement A concave shaving mirror has a radius of curvature of 40 cm. It is positioned so that the (upright) image of a man's face is 3.30 times the size of the face. How far is the mirror from the face? Homework Equations M = Si/S 1/S + 1/Si = 2/R The Attempt at a...
  15. K

    Concave Mirror Image Magnification Calculation

    Homework Statement A concave mirror has a focal length of 33.5 cm. Determine the object position for which the resulting image is upright and five times the size of the subject. Answer in units of cm. Homework Equations m=-(di/do) (1/di)+(1/do)= 1/f The Attempt at a Solution...
  16. C

    How Does a Concave Mirror Affect Image Characteristics?

    Homework Statement What is the relative size, orientation, and type of image from an object placed at the centre of a concave mirror? Homework Equations I drew a ray diagram for this. The Attempt at a Solution The image will be erect, the same size and real. That seemed...
  17. P

    Positioning of a concave mirror

    lenses and mirrors?? hi all, i was wondering what would happen if a convex lens and a concave mirror were set up one after another, the convex len being first to receive the light. how would this work in spot lights? i don't see howa spot light can have a tightly focused spot on a stage, i...
  18. S

    Concave Mirror and objects distance

    Homework Statement A concave mirror (f = 44 cm) produces an image whose distance from the mirror is one-fourth the object distance. (a) Determine the object distance. cm (b) Determine the (positive) image distance. cm Homework Equations 1/do +1/di =1/f do=object...
  19. P

    Concave Mirror Lens Ray Diagram

    Homework Statement A person 1.62 m tall wants to be able to see her full image in a plane. a) What must be the minimum height of the mirror? b) How far above the floor should it be placed, assuming that the top of the person's head is 15 cm above her eye level? Draw a ray diagram...
  20. H

    Focal length of a concave mirror

    Homework Statement Focal length of a concave mirror. This was an experiment, done in class. I was required to collect a light globe:(of course with a power source) for the object, paper:screen/image, and a concave mirror. I created the images, of the globe filament, to the screen...
  21. R

    Concave mirror producing an image 3 times larger than the object

    A concave mirror has a radius of curvature of 0.5 m. At what position should and object be placed to produce an upright virtual image that is 3.0 times as large as the object? I have just no clue for this question,, but I have to understand it T.T can any1 help me please>..
  22. R

    Understanding Image Formation in Concave Mirrors

    As the object is moved along the principle axis toward the vertex of a concave mirror, the type of image changes. Where does the change in type of image occur? Explain why, in terms of the path of the light rays. I just don't know what it means, can you guys help me with this question?... I...
  23. G

    How Does Magnification Change When Switching from Convex to Concave Mirror?

    A spherical mirror is polished on both sides. When used as a convex mirror, the magnification is +1/4. What is the magnification when used as a concave mirror, the object remaining the same distance from the mirror? I started with: mconvex = 1/4 mconcave = ? doconvex = doconcave...
  24. G

    Ray Diagram for Concave Mirror: Image Position & Height

    A 1.0 cm high object is situated 11.0 cm in front of a concave mirror that has a radius of curvature of 8.00 cm. Using a ray diagram drawn to scale (the mirror must be drawn to scale): (a) measure the location of the image: 6cm (infront of the mirror) (b) measure the...
  25. J

    Concave mirror and virtual image

    we used a concave mirror and a candle for an experiment when the candle wa placed between the vertex and the focus of the mirror (f=12.7cm) a virtual image appeared behind the mirror. We measure the image distance approximately by pointing a finger towards where the image might be and got...
  26. J

    Experimenting with a Concave Mirror and a Candle

    we used a concave mirror and a candle for an experiment when the candle wa placed between the vertex and the focus of the mirror (f=12.7cm) a virtual image appeared behind the mirror. We measure the image distance approximately by pointing a finger towards where the image might be and got...
  27. J

    Why Did an Image Form at the Focal Point in Our Concave Mirror Experiment?

    We did an experiment with a concave mirror Concave mirror was placed on optics bench and a candle was placed at designated spots. A screen was used to see where the image was projected. But a strange thing happened. When the object was placed at the focal point, image was projected on the...
  28. D

    Uncover the Mystery: Why You See a Real Image in a Concave Mirror

    Hi Why is that you can see a REAL image in a concave mirror when you are looking into the mirror?[/FONT] i tried searching the answer on the net but could not find the answer. please help thanx in advance.
  29. J

    Help with concave mirror question

    here's the question asked: Find the two locations where an object can be placed in front of a concave mirror with a radius of curvature of 36 cm such that its image is five times its size. In each of these cases, state whether the image is real or virtual, upright or inverted. 1. i have...
  30. T

    Radius of Curvature of a 10cm Concave Mirror

    A concave mirror has a focal length of 10 cm. what is its radius of curvature?:eek: i have absolutely no idea how to solve this, please help:cry:, any advice is greatly appreciated:smile:
  31. M

    An image is magnified by 2.50, concave mirror confusion wee

    Hello everyone< i think I'm on the right track but now I'm stuck. Here is the problem: A concave shaving mirror has a radius of curvature of 37.0 cm. It is positioned so that the (upright) image of a man's face is 2.50 times the size of the face. How far is the mirror from the face? Here is my...
  32. C

    What is the object distance for a concave mirror?

    Hey eveyone, I have a concave mirror and an object x distance away from the mirror. I am wondering if anyone knows where you measure from in order to determine how far away the object is from the mirror. Is it from the object to the center of the concave mirror? Thanks, ccflyer
  33. C

    Finding height of image for a concave mirror

    Ok, there's something I just don't understand. I know that to find the height of an image (hi), you need to use the magnification equation m = -di/do = hi/ho. And for this question, the focal length (f), distance of object (do), and distance of image (di) are given. Now, if I want to find the...
  34. M

    How Do Double Concave Mirrors Create a Floating Image?

    I am trying to figure out how those double concave mirror set ups work to create an image above the mirror. Does anyone know what I am talking about? You have 2 [spherical] concave mirrors, both with the same radius of curvature (and thus the same focal length), one facing up, and the other...
  35. H

    Converging lens and Concave mirror

    A converging lens (convex) and a concave mirror, both of focal length 5.0 cm, are arranged with their axes in line. The lens and the mirror are 10.0 cm apart and a candle is placed 3 cm infront of the mirror. By using a ray diagram or some other metho, find the location of all the images...
  36. K

    How Do You Determine Object Location and Magnification in a Concave Mirror?

    Well, here is the problem: A girl has her 2-cm high eye 12 cm directly in front of a concave mascara mirror or focal length 18 cm. Where is the object located, and what is the magnification? I'm really lost on this one. EDIT: Sorry, I just realized this would be better suited for the...
  37. C

    Image Location for a Double Concave Mirror (-20 in Focal Length)

    if a double concave mirror with a focal length f = -20 inches is used , where does the image seem to be located , if the image is 30 feet away from the lens first i converted the 30ft to inches and got 360inches used formula 1/p + 1/q = 1/f .0028 + 1/q = -.05 1/q = -.053 q = -18.9...
  38. D

    Diverging Lens and Concave Mirror

    Can someone get me started on this, I know how to work a diverging lens and a concave mirror, just not together. The problem: A concave mirror with a radius of curvature of 20.0 cm is placed 25.0 cm from a diverging lens with a focal length of 16.7 cm. An object is placed midway between the...
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