Physics 11.1.3a - Spherical and Parabolic Mirrors

[61miroman]

I was thinking of light waves like fluid . Tne photons don't have atomic weight so they can't take up space. Thanks again.

[61miroman]

Thanks for the explain. The multiple light waves ocupying the same point at one time helps out.

[derekowens]

@61miroman Glad that helped. Here's another way to think about it: Rather than the light moving faster, the brightness becomes more intense as the rays converge.

[61miroman]

Ok it bounces of at 186,000 miles an hour but to get throught the focal point does oit speed up? Was my question. Like a garden hose if you restrict it it produces more pressurewhich increases velocity etc. Thank you.

[derekowens]

@61miroman I think I get your question, and the answer is definitely No. The light does not move faster due to restricted flow like water in a conduit. Multiple light waves can occupy the same point at one time. The "interfere", that is they mathematically add up, but the speed remains constant.

[61miroman]

Good video thanks for the enlightment. When the light is concentrated to the focal point does it speed up ? And if so what would be the mathematical formula. Could the focal point be passed through a tube to make a ray. Possibly for space travel? But thats at a later date. First is to find out if the ligh speeds up and by how much. If it speeds up lets say double the speed or faster we might have a eurika moment. As far as I know it's only 1x the speed of light so far. I am trying to multiply.

[derekowens]

@61miroman "Enlightenment!" Haha, I get it! No, the light does not speed up when it reflects. It strikes the mirror moving at 186,000 mi/s, and it bounces off at 186,000 mi/s.

[Marichuy92]

@TheDevilvivek Because maybe, you couldn't look at yourself in the mirror if you saw your image turned on backwards. I mean, that's a response from the simple non-mathematic human, LoL o_O (srry 'bout my grammar)

[cdizzle609]

you good sir are the sex!

[TheDevilvivek]

if real images formed by concave mirrors are located on front of the mirror, why do we see the image on the mirror itself, as if it were located behind the mirror?

[TheDevilvivek]

i am having a problem , when i see the ray diagram of concave mirror ( except in which object is placed between focus and vertex)all 5 ray diagrams i see image is formed below object . if object is placed at c image is also placed at see c this mean image is formed in surrounding not in mirror , please please help me out

[TheDevilvivek]

can you please tell me centre of curvature of concave mirror

[Clipster15]

Now, how to build one of these mirrors?

[MasterThief1324]

In addition to coming to a focus, paraboloids also reflect incoming EM waves back to its source correct?

[derekowens]

@MasterThief1324 Incoming parallel light waves will be concentrated at the mathematical focus of the parabola. In the reverse process, the source of light is at the focus, and the light waves are reflected out in a parallel fashion, like a spotlight.

[MasterThief1324]

@derekowens Yep -- but I meant to ask about the direction of the light after it had passed through the focus.

[MasterThief1324]

@MasterThief1324 A follow-up question is if you lined your sight towards the face of a parabolic mirror, would you see your reflection?

[derekowens]

@MasterThief1324 Oh, I see. Yes, that is correct. After passing through the focus, it will again be reflected back to its source, assuming that the paraboloid is large enough so that ray's path intersects the paraboloid again.

[usaswim323]

Fantastic lecture.

[bates507]

does the same work with speakers. what im saying is, is it possible to make a parabolic speaker cone? shot in the dark i know lol

[derekowens]

@bates507 You can make a parabolic sound reflector. In fact, at the Fernbank Science Center here in Atlanta, they have two huge (5 feet maybe) paraboloids facing each other, like this:  ( )

The are across a large room from each other. You can put your ear at the focus of one and hear a very quiet whisper from someone at the focus of the other. It's very effective, and an impressive demo.

[bates507]

@derekowens awesome, thanks for the reply :)

[imanoob4]

Can light go through other light perpendicularly and still have 99.9999% of the light go through?

[derekowens]

@imanoob4 As far as I know, two beams of light can go through each other at right angles, or at any angle for that matter, and each beam will have 100% of the light go through. Someone can feel free to correct me if I'm wrong, though.

[EPhantom125]

another reason why the light will never come out of the parabolic mirror perfectly straight, is that even if you had a perfect parabolic mirror, and had the perfect bulb in the perfect place, the light rays would hit one another and knock each other off course.

[derekowens]

@EPhantom125  Actually, the wave nature of light would be apparent here, not the particle nature. The light waves would pass through each other and continue on course rather than bouncing off of each other.

[BogMonkey53]

Nice one. thanks for uploading

[cool123vin]

Thanks! I'll use this 4 my physics project, about mirrors.

[derekowens]

That's okay with me, as long as you are fluent in Spanish. And thanks for asking. Tell me when you have one of them done and I'll take a look.

D.O.

[mupo1811]

man do you mind if i put spanish subtitles on the videos and re-uploadthem later? I would do it for free and give you the due credit for it.

What do you say?

[kyzill]

this is pretty damn good