Convex lenses | Geometric optics | Physics | Khan Academy

[@FilezillaDownload]

Thanks Khan for posting these free educational videos, you're doing a wonderful service.

[@salmael-amin159]

Yess true he has a great role in me getting such high marks in physics

[@fleshcookie]

the car analogy really does justice to these problems. beautiful Sal

[@tmath6861]

the car analogy is like the greatest thing i have heard. it makes perfect sense now.

[@leekelly4574]

"Let me save it so I can use this for the future" HE IS SO PROUD OF HIS DRAWING i love it HAHAHHA

[@CalebTsai]

Khan-vex

[@CalebTsai]

xd

[@Nitro0xide]

xD!!

[@metastag]

@Abdullah Kamal 'Khan' as in Khan Academy, 'vex' as in Convex. :)

[@jalapenosmepeno8458]

Man, I love your work. you have made over a thousand videos just to help us learn. You have a good heart, thank you :) I appreciate it.

[@ansahsiddiqui1384]

sal i just wanted to say thank u soo much i just scored 2000/2000 in my entrance test by ur videos...

[@mallutravelersupport7240]

Lier

[@salmael-amin159]

@@mallutravelersupport7240 go find a life its none of your business

[@atifahmed204]

An alternative to car analogy is, (if you dont understand the car thing or it takes you some time to realise) let the medium in which light travels faster out of the two given media (air in case of glass and air(2 media)) be called the "rarer medium" and the other medium in which light travels slower comparatively to the first medium(here it is glass) be called the "denser medium", so when travels from rarer medium to denser medium it will move towards the normal/perpendicular, its opposite is when light travels denser to rarer it will move away from the normalJust remember DRA (denser to rarer-->> away); RDT (rarer to denser-->>towards) Hope this helps you :)

[@BenjaminBorgbeno11180]

light in a vacuum has a refractive index of 1. In Denser media(transparent objects), light travels slower. The speed of light is differnent in water that hhas a refractive index of 1.47 than in air with a refractive index of 1. Using the mita equation, one can find the constant- speed of light in air/speed of light in water. Hope this helped

[@7MohanRaj]

He might be getting paid. But that was not the original plan. In fact, he had no plan at all. He just started this on his own, spending his own money and time, just to help students. Only later, when it became a real tangible success the corporation started to give money. So,for a selfless person, he deserves this. There is a big difference between those people who make things with money in mind and those who make things for bettering humanity and then later get recognition and then get paid.

[@cameron176]

you just saved me from lose 25% of my marks for my yearly tests with your parabolic and lens videos THANKYOU!

[@mohamedfouad6205]

ok

[@PearlLikesBirds]

I am really thankful for your videos...Physics is my favorite subject, but sometimes I can't understand the teacher and I get really stressed out, but then I watch a video of yours and everything gets clear! Thank you so much :)

[@ull893]

You are doing a great selfless service to humanity and the student world , where everybody and everyone, especially, teaching and sharing knowledge has become an industry just to make money!!!

[@michaelkoles679]

1:50 Miller's... it's parabolic-shaped now! :)

[@salvnam3125]

Thanks- very clear instructions!

[@Jellgumi]

Your better then my teacher, thank you 🤠👍

[@pekaboo6549]

Superb!!!

[@2youn8]

1 hour class and the whole class doesn’t get anything. Khan saves the day again

[@lopamudrakar5680]

U have killed the confusion.

[@shinuito]

@Rivoluzzjoni i'd think they're close to being on par anyway. they're both really easy and interesting to listen to

[@kal7708]

thank you so much! this is such a great explanation

[@nidaawais3557]

Thanks

[@sandeepdash3919]

thanks really gr8!

[@lopamudrakar5680]

Superb!!! U r amazing!!

[@rajeshvelamarthi2]

Very useful and informative videos , Thanks to team.

[@AlphaCrucis]

Wow you're doing optics now? Or is this going to be part of the physics playlist?

[@BankruptGreek]

The Fou,s point!

[@paddy999ify]

has he done any videos on the eye.

[@vishnudarsan5343]

Thnk u khan

[@chispee]

UR AWSOME !!!!! just awsome

[@oil-qw5sm]

Can anyone help me with this ? The image of an object formed on the screen by a convex lens has height a. By moving the lens towards the screen , it is found that there is a second lens position at which another image of height b is formed on the screen. Prove that the height of the object is (ab)^0.5 .

[@christophersteyn3861]

Thats funny because Sal is payed millions of dollars by the Gates Academy to make these videos :P but I still agree with you, it is incredibly selfless to dedicate so much time to teaching people for free.

[@jemappellelanoosh1743]

Ty

[@falmingo513]

What App Are yo Using? 🤔

[@meraydin1]

Hi Khan, I have a question but I dont know how to proceed; say I have a wall (20cm) thick, and I want to transfer light from outer side to inside. outer side looks at the sky, inner side is dark. What I want to achieve is illuminate dark side. Can I do it with two half spherical lenses with f=10cm?

[@meraydin1]

can anyone help?

[@meraydin1]

or do I need a third lens?

[@meraydin1]

@@mohamedfouad6205 I prefer to ask your mother since my dad has passed 15 years ago.

[@meraydin1]

@@mohamedfouad6205 are you a m* or what? what is your problem? I just asked a question. maybe you should see a doctor.

[@xsillah3623]

@@mohamedfouad6205 Not cool?

[@adityamudgal0]

AWSOME

[@lakshmicbr9998]

i have a small question where should the object be placed i.e where? in between of the light source and lense? any formula to calculate that???

[@himanshupriyadarshi1186]

The Len formula perhaps?

[@Genghiskaran]

what physics level is this ? i didnt learn this in my first physics class in collge

[@xetrius]

Time: 1:36 Quote: "something in which light travels slower." I thought that the speed of light was always the same?

[@mdtoufiquzzaman9118]

Thats because light travels through a transparent medium at a lower speed than in vacuum or air

[@muhammadshafay3713]

Light travels at different speeds in different velocity

[@changjin1229]

great

[@pascalbarlay497]

This guy is a God

[@conn14]

i understand how the rays move through the lens, but how come when you look through a magnifying glass, the picture/object is not inverted?

[@sofiaswer6982]

dark colours cant see much :(

[@DeneuveBrutus]

all hail da khan

[@TruthMovement330]

Only in a vacuum.

[@hades5219]

i didnt get this at all

[@Topgearfreak132]

i love you

[@adityamudgal0]

LENSE

[@tomsellers9514]

y is he so subed

[@Chelsea-gs7qj]

Im so confused. When is it a virtual image and when is it a real image?? And I thought he said in the last video that the outer side of the lens was reflective so why is the ray going through?

[@ailurophile4341]

What

[@falmingo513]

You*

[@ananyasinghable]

my name is khan, and i am not money minded ! :D

[@montyhorseman4264]

What is wrong with you

[@khalfanzaki9955]

no ur name is Ananya Singh

[@user-vm9jn4dt1i]

@@khalfanzaki9955 lol😂😂

[@dark-ff135]

Does anyone know what is Freefire?

[@user-vm9jn4dt1i]

yep

[@dark-ff135]

@@user-vm9jn4dt1i Ok where are you from

[@surbvtr]

vagina!