A mirror is an object that reflects an image. Light that bounces off a mirror will show an image of whatever is in front of it, when focused through the lens of the eye or a camera. Mirrors reverse the direction of the image in an equal yet opposite angle from which the light shines upon it. This allows the viewer to see themselves or objects behind them, or even objects that are at an angle from them but out of their field of view, such as around a corner. Natural mirrors have existed since prehistoric times, such as the surface of water, but people have been manufacturing mirrors out of a variety of materials for thousands of years, like stone, metals, and glass. In modern mirrors, metals like silver or aluminum are often used due to their high reflectivity, applied as a thin coating on glass because of its naturally smooth and very hard surface.
A mirror is a wave reflector. Light consists of waves, and when light waves reflect off the flat surface of a mirror, those waves retain the same degree of curvature and vergence, in an equal yet opposite direction, as the original waves. The light can also be pictured as rays (imaginary lines radiating from the light source, that are always perpendicular to the waves). These rays are reflected at an equal yet opposite angle from which they strike the mirror (incident light). This property, called specular reflection, distinguishes a mirror from objects that diffuse light, breaking up the wave and scattering it in many directions (such as flat-white paint). Thus, a mirror can be any surface in which the texture or roughness of the surface is smaller (smoother) than the wavelength of the waves.
When looking at a mirror, one will see a mirror image or reflected image of objects in the environment, formed by light emitted or scattered by them and reflected by the mirror towards one's eyes. This effect gives the illusion that those objects are behind the mirror, or (sometimes) in front of it. When the surface is not flat, a mirror may behave like a reflecting lens. A plane mirror will yield a real-looking undistorted image, while a curved mirror may distort, magnify, or reduce the image in various ways, while keeping the lines, contrast, sharpness, colors, and other image properties intact.
A mirror is commonly used for inspecting oneself, such as during personal grooming; hence the old-fashioned name looking glass. This use, which dates from prehistory, overlaps with uses in decoration and architecture. Mirrors are also used to view other items that are not directly visible because of obstructions; examples include rear-view mirrors in vehicles, security mirrors in or around buildings, and dentist's mirrors. Mirrors are also used in optical and scientific apparatus such as telescopes, lasers, cameras, periscopes, and industrial machinery.
The terms "mirror" and "reflector" can be used for objects that reflect any other types of waves. An acoustic mirror reflects sound waves. Objects such as walls, ceilings, or natural rock-formations may produce echos, and this tendency often becomes a problem in acoustical engineering when designing houses, auditoriums, or recording studios. Acoustic mirrors may be used for applications such as parabolic microphones, atmospheric studies, sonar, and sea floor mapping. An atomic mirror reflects matter waves, and can be used for atomic interferometry and atomic holography.
Dear PF Forum,
I have a question again about Doppler effect in relativity.
Before I ask about mirror and lamp, I want to refresh the discussion again
as in my previous thread: https://www.physicsforums.com/threads/doppler-for-light.823942/
The formula for Doppler factor for light is.
##f =...
Let's say I have a linearly polarized laser beam, and I focus it to a small spot using a parabolic mirror. Does the light retain its polarization at the focal point? Why or why not? I understand that flat mirrors and concave/convex mirrors preserve linear polarization, and I would like to make...
Homework Statement
Why is is that when we look in a mirror we expect to see a reflection equally as bright as the real image, but when we stand in front of a cliff and clap our hands we don't hear an echo as loud as the original sound?
Homework Equations
R = (z2 - z1)/(z2 + z1)
The Attempt at...
Homework Statement
a convex lens forms a real image of a point object at a distance of 50 cm from convex lens. a concave lens is placed 10 cm behind convex lens on image side. on placing a plane mirror on the image side and facing the concave lens it is observed that final image now coincides...
In fluorescence microscopy, dichroic mirrors reflect light under a critical wavelength (used to excite the sample) and transmit light over a critical wavelength (emission light from the sample). Are there mirrors that reflect two different wavelengths of light and transmit the rest? Essentially...
As involvement of emitter resistor in current mirrors has certain drawbacks like restricting the output voltage range to a lower value..thus in order to cancel the draw back of emitter resistors they say to use a
Widlar current mirror …Widlar current mirror is designed to provide very small...
In a current mirror circuit ..presence of an emitter resistor (R1 and R2) increases the output resistance which minimises harms of early effect...how?
why its advantageous to have a high output resistance in current sources/current mirror circuits?
Hi Everyone,
A question in my latest Physics I lab wishes for a proof showing that if a laser beam is incident on a mirror that is then rotated an angle θ the beam is deflected an angle 2θ.
I attempted to prove this geometrically below. In the diagram the angle γ, is the angle of deflection...
Homework Statement
A plane mirror is placed at the origin. A converging lens with a focal length of 5.00m is located at x=12.50m. A object is placed at x=22.5m
Find the final location of the image in terms of its X coordinate & magnification.
Homework Equations
1/q + 1/p = 1/f (lens)...
Homework Statement
The question is attached in the jpeg file.
Homework Equations
1/do + 1/di = 1/f
The Attempt at a Solution
First reflection : 1/100 + 1/di = 1/80 , di = 400cm ( To the right of the lens )
This means that the image created is a virtual image since it is behind the lens.
So...
Homework Statement
A shoplifter is spotted using a convex mirror, in which the image appears to be 22.0cm behind the mirror, which has a focal length of 24.0cm. HIs apparent height, in this image, is 14.0cm tall.
A)How far away is the shoplifter from the mirror?
B) How tall is the shoplifter...
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...
Homework Statement
You wish to obtain a magnification of -2 from a convex lens of focal length f. The only possible solution is to:
A) place a virtual object at a distance 2f/3 from the lens.
B) place a virtual object at a distance 5f/3 from the lens.
C) place a real object at a distance...
I am going to make a Dobsonian telescope. Primarily a 6" f/8. I have no idea what the secondary mirror size would be an its distance from the centre of the primary. I have been told that if the secondary is too small then the effective aperture would be reduced. And i do not understancd these...
Homework Statement
Homework Equations
ID= kn (Vgs - Vth)^2
The Attempt at a Solution
I asked to find the current I D , M2. [/B]
I think in order to solve this question I need to find Vgs but how do I do that?
RC1 = 2k ohm
R = VDD - Vgs / I D ,M2
VDD = 5V , and R = 2k ohm and I have 2...
Homework Statement
Hey, so there is a light bulb above a tank of water which has a mirror at the bottom. I am trying to find the apparent depth of the image of the light produced by the mirror. Finding the apparent depth of the mirror is easy, but I am confused on what to consider the object...
Homework Statement
An object is placed in front of a convex mirror with a 45.6-cm radius of curvature. A virtual image half the size of the object is formed. At what distance is the object from the mirror?
Homework Equations
1/f=1/d0+1/di
hi/h0=-di/d0
The Attempt at a Solution
hi=-1/2h0...
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...
Homework Statement
A mirror moves perpendicular to its plane with speed βc. A light ray is incident on the mirror from the “forward” direction (i.e., vm · vl < 0, where vm is the mirror’s 3-velocity and vl is the light ray’s 3-velocity) with incident angle θ (measured with respect to the...
I am moving a small glued mirror (~10 gram) attached to a piezoelectric stage:
http://www.physikinstrumente.com/product-detail-page/s-330-300700.html
The mirror moves back and forth for a few milliseconds using a PID control loop, the range is about 2mrad.
I want to increase the angular...
I was wondering if there are objects near our galaxy that can reflect light from the Milky Way back to us for observation. If so, maybe they can provide information about the shape of the galaxy, for example. I'm sure there would be other interesting applications.
I was thinking about it...
Homework Statement
How much of a wall 3m behind you can be observed in a 5 cm square mirror which is held centrally at a distance of 10 cm from your eye?
Homework Equations
None that I can think of. I think this is straight geometry.
The Attempt at a Solution
I know I have to use similar...
Homework Statement
When a T.rex pursues a jeep in the movie Jurassic Park, we see a reflected image of the T.rex via a side-view mirror, on which is printed the (then darkly humorous) warning: “Objects in mirror are closer than they appear.” Is the mirror flat, convex, or concave?
Homework...
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...
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...
I read that concave mirrors are part of a sphere, and concave mirrors can also be expressed in a parabola equation, but a parabola equation is expressed as #4py=x^2# and a circle as #x^2+y^2=R^2#. So the two can't be the same right? Can someone please explain this? Thank you in advance :)
Homework Statement
A vertical mirror is placed at the origin. A ray of light coming from A is reflected by the mirror so that it passes through B. How far from the bottom does the ray hit the mirror? The coordinates are A = (11.4, 15.9) and B = (15.9, 4.7), in centimetres.
Homework...
I'm interested in understanding what effect does long-term radiation and microdust exposure would do to the surface roughness of a high-precision mirror like the one on the Hubble. Since it has been on orbit for 24 years, it provides an unique opportunity to estimate accumulated environmental...
I understand that 4% of the light is reflected back from the glass surface in a thick glass mirror. But why 4%? Why not 5% or 10%? Will this percentage change if the glass has a lower refractive index?
Homework Statement
[/B]
Two parallel mirrors that face each other are placed along and perpendicular to the x-axis at x = +7.40 m and x = -7.40 m. Assume that a point source of light is placed on the axis at x = +3.30 m. In principle, there will be an infinite number of images generated...
how image is formed on a plane mirror , when light bulb is switched on, photon strikes a point on an object ( for ex.a ball) and from their the photon strikes the mirror and form incident angle and reflective angle , my question is does the photon carry the image with it ? or does it act like a...
When you collimate a point source using an off-axis parabolic mirror (OAP) with a circular shape, the beam area of the collimated light becomes more and more elliptical (x-dir. is smaller than y-dir.) as the off-axis angle is increased. Is there a reason why this happens? And is there a way to...
Hello/...
Give me reference or ready made material ...for following
mounting method of mirror in space telescope
and its mechanical Design and structure for mounting mirror.
I attached a picture with 3 questions?
My first question is, I know that for a convex or concave mirror, If I shine a light at an angle to the middle of the mirror the light will reflect with the same angle. Will the angle be the same if I shine the light at the concave/convex mirror if it...
So based on String theory, when doing a Double Slit Style Experiment when an observation is made it is a particle and when on observation is not made, it is a wave pattern.
What exactly do the Interference patterns mean? Basically what I research was this... Doe it means that in the...
Hello Everyone,
I was just thinking about a question about mirrors and this specific question has been making me thinking about it for a long time and I still couldn't find the answer.
The question is simply about mirrors.
A mirror reflects images that are significantly altered by being...
I need to do something for a project. Basically, I need to be able to project a clear image onto a mirror while still being able to use the mirror when the projector is not in use. Is there a way to do this/a cheap coating I can put on a mirror to accomplish this?
Thank you!
Hello,
I have access to a pretty big telescope, at least when compared to others I've played with. I'm itching to set it up but the mirror is not in great shape. It has been in storage for a long time and there looks to be some corrosion.
I was wondering if there is anything I need to be...
I am looking at a reflection of an object that is on the floor in a plane mirror. If the object is a certain distance away from the mirror, how would I use the properties of similar triangles to calculate the positions of the points on the mirror that each ray (one to top of eye and other to...
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...
Homework Statement
A small object is located on some distance from a converging lens. At some distant behind a converging lens lies a flat mirror. The resulting image is exactly at the same location as the small object. Why can we deduce that the object is located in the focal point of the...
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...
I saw a clever aftermarket rear backup mirror on a minivan recently, and I'd like to buy one for my Suburban.
It's about 9" in diameter, and attaches to the rear door of a minivan or SUV at the door seam along the side near the top. This makes it visible through the rear window, so you can...
Homework Statement
A lens of focal length 0.8m is 1.0 m to the left of a mirror of focal length -0.500m. An object is placed 1.00 m to the left of the lens. Light goes through the lens, bounces from the mirror, and goes through the lens again, this time from the right.
Homework Equations...
Shiny lawn spheres placed on pedestals are convex mirrors.
One such sphere has a diameter of 40 cm. A
12 cm long robin sits in a tree 1.5 m from the sphere.
(a) Where is the image of the robin?
(b) How long is the image?
f=R/2 to find radius
1/v=1/f-1/u to find image distance (the mirror...
Homework Statement
Below is a {MATLAB}code for Bragg mirror. How can I implement the code to create an FP resonator?
Homework Equations
The Attempt at a Solution
%User input parameters
num_layers = input('The Number of Layers in the structure = ');
r_index1 = input('refractive...
Homework Statement
While you were looking at the reflection of your feet in a plane mirror,
you saw a dark spot on the glass. Assuming your height is 1.50 m, and that
the eyes are located 0.1 m below the top of the head
(a) What is the distance between the spot and the floor?
(b)...