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. radish

    Concave mirror reflection, problems with drawing setup

    1/f = 1/Di + 1/Do 1/Di = 1/f - 1/Do 1/Di = 1/4 - 1/5 1/Di = 1/20 Di = 20 cm In my drawing i had a focal point of 4 so a center of circumference of 8 and I had an object with a height of 1 cm placed 1 cm after the focal point, so 5 cm, away from the mirror. The distance of the image that i...
  2. M

    Concave mirror reflecting a point lamp, that create a wider beam

    I've look if there was any way to get the "image size" or a ratio to use the Mirror Equation to find the focal length, but nothing. I think it's base on some geometry, but I don't see the relation.
  3. N

    I Two mirrors to focus sunrays into a tiny spot -- possible?

    Hi guys, i am Nenad Komjenović from Bosnia and Herzegovina, I am just a regular guy, who likes geeky stuff and i don't know physics, so i wanted to ask you guys for an opinion. I was inspired by the "Markus Kayser - Solar Sinter Project" Youtube video, in which the guy used fresnel lens to...
  4. N

    Virtual and real image with concave mirror at 45 degrees

    I have a spherical concave mirror with focal length of 65cm, radius of curvature of 130cm. I hold the mirror close to the eye at approximate 45 degrees and I reflect an object below it as shown in the image. The distance between the object and the mirror is 90cm, that is more than the focal...
  5. P

    Combination of thin lens and concave mirror

    I created the following ray diagram to help me solve the problem: Then I applied the mirror equation 3 separate times. However, the final image distance I got is wrong. I'm wondering if I'm mistaken in taking the last object distance to be negative. However I only have one more try to get this...
  6. K

    ABCD matrix formalism for concave mirror

    Hello! I need to calculate the ABCD matrix for a thick concave mirror, in the situation in which the light comes from the plane side of the mirror, and it is the concave part that is coated (for reference, I have a Fabry Perot cavity with 2 concave mirrors, and I want to mode match the laser...
  7. S

    Understanding Reflection of Light on a Concave Mirror

    My Basic Question is- Why can we see our inverted and real image inside a concave mirror when the image is formed in front of it and not behind? If you say that our eyes tries to image the real image formed by mirror on the mirror itself then- Imagine a situation where we have a concave mirror...
  8. S

    Correct statement about a concave mirror

    Option (a) is wrong because if the person is standing at the focal point of the mirror, no image will be produced Option (b) is wrong because concave mirror can produce magnified image Option (c) is wrong because concave mirror can produce upright image Option (d) is wrong because sharp image...
  9. P

    Can a convex reflection be corrected using a concave mirror?

    If one took a photograph of a reflection from convex reflective surface. Could one use concave mirror to obtain the original undistorted image?
  10. D

    How we see image inside the concave mirror when object is beyond C?

    In concave mirror, when object is beyond C ( centre of curvature) our traditional Ray diagrams show a real and inverted image formed between C and F. But at the same time, if we look directly into the mirror and remove the screen, we see an inverted image which appears to be inside the mirror...
  11. Akash47

    The size of the image of the Sun

    Homework Statement The focal length of a concave mirror is f=20 cm. It is directed towards the sun and the sun makes an angle= 1° at the pole of the mirror. What is the size of the image of the sun? Homework Equations 1/u +1/v =1/f ...(i) ,magnification= v/u= l2/l1 where l1 =size of the sun,l2...
  12. N

    About a concave mirror with a large focal length (1000mm)

    I have a Cassini PM-160 spherical mirror used in telescopes as the primary mirror. The mirror is concave with a radius of curvature of 2600mm and focal length of 1300mm. I have a very basic question. If an on object is located beyond the focal length of a concave mirror then the virtual image...
  13. N

    B Are the Sun's rays reaching us always parallel?

    My book says that the Sun's rays reaching us are always parallel. See this image Are the Sun's rays reaching us always **PARALLEL rays**? I will be thankful for help!
  14. jlmccart03

    Location of object on axis of concave mirror?

    Homework Statement Where on the axis of a concave mirror would you place an object to get a half-size image? Express the object distance in terms of the focal length f. Follow the sign convention. Homework Equations (1/q)+(1/p)=(1/f) f=(2/R) The Attempt at a Solution I attempted to use the...
  15. KT KIM

    Apply Fermat's principle to a Concave mirror

    I am now taking optics class at my school. Fermat principle can be applied on mirror of course. Then what about Concave mirror? According to the calculus of variation. the optimized path(actual path of the light) should be the shortest path. but in the concave mirror case, it goes through the...
  16. P

    Imaging by cylindrical concave mirror

    Consider an upright cylindrical concave mirror with a point source located at the focal point of the mirror. By upright I mean that the mirror is plane in the vertical direction and a concavity in the horizontal plane. Now it seems likely that you would see a virtual image of the point source...
  17. RabbitWho

    Understanding Focal Length: Solving for Image Position with 1/u + 1/v = 1/f

    Homework Statement u= distance from the object to the mirror v = distance from the image to the mirror f = focal length I don't understand what they are talking about and I would like to 2. Homework Equations If the image is real 1/u + 1 v = 1/f If the image is virtual 1/u - 1/v = 1/f The...
  18. S

    Concave mirror: Reflected rays do not meet at one point

    I have drawn a diagram of the incident and reflected rays of an object by the concave mirror. Red color shows the incident rays, black color shows the normals drawn from the center of curvature, while green color shows the reflected rays. Shouldn't all the reflected rays meet at one point. Any...
  19. A

    How to solve for distance of object with a concave mirror?

    Homework Statement An object is placed a distance do in front of a concave mirror with a radius of curvature r = 6 cm. The image formed has a magnification of M = 4.3. Solve for the object's distance. Homework Equations M = -di/do (1/do) + (1/di) = 2/R = 1/f The Attempt at a Solution I've tried...
  20. V

    Position of Final Image in Concave Mirror with Glass Block

    Homework Statement A glass block of thickness 60 cm and refractive index 4/3 is placed in front of a concave mirror. A light source is then placed on the center of curvature of the concave mirror. Find the position of the final image formed. (Focal length is 30 cm) Homework Equations...
  21. D

    Why does the two concave mirror illusion looks realistic wh

    while a simple concave mirror projection does not?Hi, I'm really not sure where does this question go, but perhaps this is as good a place as any... If not, then I would appreciate a referring to the right place. So, I have encountered this nifty, decades old, illusion created by combining two...
  22. Max Matiauda

    Image formed from object at focal point of concave mirror

    The question posed: "An object is located to the right of a mirror that in concave in its [the object's] direction. If the object sits on the focal point of the mirror, what answer best describes the image formed?" Our class is united in the notion that as the rays would be parallel...
  23. L

    Image formed by a plane-concave lens and a concave mirror

    Homework Statement An observer looks at an object of height 2 cm through a plane-convex lens of radius 20 cm and refraction index 1.5. There's a concave mirror of radius 30 cm 40 cm behind it, and the object is at the same distance of both the lens and the mirror. Find the images formed by the...
  24. Suraj M

    Refraction through a glass slab + reflection off a concave mirror

    Homework Statement An object is placed 21 cm in front of a concave mirror of radius of curvature of 10 cm. A glass slab of thickness 3 cm and RI =1.5; is then placed close to the mirror. Find the position of the final image. Take distance of closer side of block as 1 cm from the mirror...
  25. B

    Mirroring using a concave mirror

    Homework Statement An object is mirrored in a concave mirror. Construct the image of the object using two rays from the object. (draw in the picture) Homework Equations None needed? The Attempt at a Solution So the upward arrow is the object, f is the focal point I assume. I am to draw two...
  26. P

    How Do You Calculate the Focal Length of a Concave Mirror with a Moving Image?

    Homework Statement A light bulb is placed 10.7 cm in front of a concave mirror. When the concave mirror is replaced by a plane mirror in the same location, the bulb's image moves 4.00 cm closer to the mirror. Calculate the focal length of the concave mirror. I am given: do: 10.7 and 4.00 is...
  27. W

    Optical System with Diverging Lens and Concave Mirror

    Homework Statement A diverging thin lens and a concave mirror have focal lengths of equal magnitude. An object is placed (3/2)f from the diverging lens and the mirror is placed a distance 3f on the other side of the lens. Using Gaussian optics, determine the final image of the system after two...
  28. S

    Silvering of Plano-Convex Lens

    If the plane surface of a plano-convex lens in silvered then which of the following statements is true? 1. it acts like a convex mirror 2. it acts like a concave mirror 3. it acts like a concave lens 4. no changemy attempt--- the incident ray on the convex surface of the plano-convex will...
  29. T

    What is the image distance for a concave mirror using the mirror equation?

    Homework Statement B) Using the mirror equation, find the image distance. Homework Equations 1/do + 1/di = 1/f The Attempt at a Solution [/B] B) do = 2cm f = 4cm 1/do + 1/di = 1/f 1/di = 1/f - 1/do 1/di = do/f(do) - f/f(do) 1/di = (do-f)/(f*do) di = (f*do)/(do-f) = (4cm * 2cm)/(2cm - 4cm)...
  30. sankalpmittal

    Problem regarding concave mirror

    Homework Statement A point object at 15 cm from a concave mirror of radius of curvature 20 cm is made to oscillate along principal axis with amplitude 2 mm. Find the amplitude of its image. Homework Equations Mirror formula : 1/v + 1/u = 1/f Here u=-15 cm , f=-10...
  31. I

    How to Position an Object for a 2.5x Inverted Image with a Concave Mirror?

    Homework Statement Where do you put an object in front of a concave mirror of focal length 10cm to produce an image that is inverted and 2.5 times greater than the object? Homework Equations \frac{1}{f}=\frac{1}{P}+\frac{1}{Q} Where: Q=Image distance from mirror P=Object's...
  32. P

    Image formation in concave mirror

    Can we see a real image with our naked eye without using a screen to capture image? Also, we all know that virtual image formation in a concave mirror will be always erect. Check out the image below. Spoon here acts as a concave mirror and the image is inverted. Why is it virtual then?
  33. S

    MHB Reflecting Ray from Concave Mirror: Parabola Focus

    A ray of light is coming along the line $y=b$,($b>0$), from the positive direction of the x-axis and strikes a concave mirror whose intersection with the $x-y$ plane is the parabola $y^2 = 4ax$,($a>0$). Find the equation of the reflected ray and show that it passes through the focus of the parabola.
  34. X

    Nonstandard Concave Mirror Optics, beyond the parabola.

    Why is the parabola the most bent, concave, effective mirror? What are some properties of a third order mirror (absolute value of x^3)? There is no uniform focal point. Shouldn't shining a light beam along a normal to the x-axis reflect off of the function multiple times? Then take this to the...
  35. L

    Finding Object Distance for Upright Image with Magnification +1.51 for Concave Mirror

    Homework Statement Suppose the radius of curvature of a concave mirror is 5.0 cm a) Find the object distance that gives an upright image with a magnification of +1.51. Homework Equations 1/Do + 1/Di= 1/f m=-di/do=hi/ho The Attempt at a Solution First i convered all cm...
  36. P

    Finding image location with concave mirror

    Homework Statement A small object is located 32.0cm in front of a concave mirror with a radius of curvature of 40.9cm. Where will the image be formed? Homework Equations tan(θ)=-h/di f=1/2R? The Attempt at a Solution Haven't been able to solve for theta. I'm not sure what...
  37. K

    Question on Optics, finding images of a pin using a concave mirror

    A pin AB, 1cm long, is placed at an angle to the principal axis in front of a concave mirror, of focal length 5cm. Point B lies on the principal axis at a distance of 4 cm. Point A is such that the angle ABP is 60°, where P, the pole, is the point where the principal axis intersects the mirror...
  38. O

    Real image from concave mirror

    "real" image from concave mirror Ok so in we are currently doing mirrors and reflections in physics and from what I learned there are 2 types of images: real and virtual. I know that a virtual image is what you see INSIDE the mirror; but what does a real image looks like? I can't find anything...
  39. R

    Image created by concave mirror, sight from a distance.

    Homework Statement A science museum has created a huge concave mirror with a focal length of 5 m, and mounted it so that it covers the entire wall at one end of a long hallway. If you stand on a center line painted down the middle of the hallway, you're on the mirror's principal axis. You...
  40. R

    Best location for a light bulb filament using a concave mirror?

    Where is the best location for a light bulb filament to be placed in a spotlight, when using a concave mirror? It makes the most sense to put it at the focal point of the mirror if you want parallel light beams but are you supposed to have parallel light beams when you use a spotlight? Or do...
  41. H

    Software to calculate diffraction figure at focal point of concave mirror?

    Classic paraboloidal mirror. Incoming flat wavefront of known wavelength (500 nm, green light), propagating parallel to the major axis of the mirror. The wave hits the mirror and is being sent back towards focus. At the focal plane, there's a flat CCD or some other light detector. Upon hitting...
  42. P

    Real Image in a Concave Mirror: Virtual Object Analysis

    how can we say that the image formed by a concave mirror is always real if object is virtual? please help
  43. P

    Calculating Image Size of Dropped Ball from a Concave Mirror

    Homework Statement "a concave mirror is placed horizontally on the ground with a focal length of 1 meter, a boy sitting on a tree above the mirror drops a 7cm diameter styrofoam ball right over the mirror 3 meters high, determine when the image will be the same size of the ball" Homework...
  44. P

    Does a perfect concave mirror act as a radiation heatpump

    if one was able to make a perfect concave mirror with half a cube shape perfect mirror in front of it ( so thermally isolated from outside with a perfect vacuum inside it) And a black body almost covering the front of the Concave mirror that is red hot and another much smaller black body in the...
  45. H

    Thin lense combined with a concave mirror

    Homework Statement Homework Equations 1/f=1/i + 1/p m=-i/p Where m is magnification, i is image distance, p is object distance, and f is the focal length. The Attempt at a Solution 1/f = 1/1.5f + 1/i i=3f I have also attempted to draw a ray diagram to use the image of...
  46. R

    How Is the Image Size Calculated in a Concave Mirror?

    Homework Statement An object 23.0 mm high is 31.0 cm away from a concave spherical mirror with a radius of curvature of 54.0 cm. What is the absolute size of the image? Homework Equations Maybe these are relevant Mirror equation in terms of focal length...
  47. A

    A small postage stamp is placed in front of a concave mirror

    Problem: A small postage stamp is placed in front of a concave mirror (radius=R), such that the image distance equals the object distance. (a) in terms of R, what is the object distance (b) what is the magnification of the mirror (c) state whether the image is upright or inverted relative to...
  48. I

    Sunlight falls on a concave mirror, where is the image formed?

    Homework Statement Sunlight falls on a concave mirror and forms an image 3.0 cm from the mirror. If an object 24 mm high is placed 12.0 cm from the mirror, where will its image be formed? a. Use a ray diagram b. Use the lens/ mirror equation c. How high is the image? Homework Equations...
  49. H

    Image formed by concave mirror; completed need someone to check

    Homework Statement A person accidentally bit his tongue and wants to examine the bite by using a concave mirror. The mirror is placed 10 cm from the bite with the result that a virtual image of the bite appears 4 times actual size. Find the parameters s (distance from object to mirror), s'...
  50. I

    Spoon Optics-Virtual Inverted image with a concave mirror

    When you look at a spoon, like at a mirror, the image of yourself appears to be on the other side of the mirror/spoon, where light does not go! So the image must be virtual! So tell me, since a concave mirror must produce a real inverted image when you are far from the focal point...