Hello viewers welcome to Elimut channel Elimut TV which is your station and you get to watch and learn. Amir Tutam is the Monday taking you through physics from three refraction so stay tuned through the lesson and do for road through. So what are the goals of this lesson? By the end of the lesson we'll be able to determine refractive index with reference to in terms of velocity. We'll also determine refractive index through successive media and we'll also look at refractive index in terms of real depth and apparent depth. So, refraction of light from the diagram you this is to help us recall that this is the bending of light when it travels from one medium to the other. So, refractive index in terms of velocity. Consider a real fright through medium one with a velocity V1 to medium to with a velocity V2. So, velocity is V1 is in V1 is greater than velocity in V2 and at the interface where we have the boundary between the two medium you will see that the light ray bends at that point. So, how do we get the refractive index? So, remember from snail's law, sine i all of a sine r refract that is the sine of the angle of incidence divided by the sine of the angle of refraction is given by the deep specimen in medium one divided by displacement in medium two which is equivalent to velocity of the fluid in medium one per unit time divided by velocity of right in medium two per unit time. Now, since the time is constant, we consider the velocity which changes and this gives us the sine the sine of the angle of incident in medium one and divided by the sine of the angle of refraction in medium two is equivalent to velocity of light in medium one per the velocity of light in medium two. So, by multiplying this using the snail's law, equiting it to the constant so that this gives us the velocity of light in the refractive index in medium one divided by the velocity in medium one is equivalent to the refractive index in medium two multiplied by the velocity of light in medium two. So, given that the refractive index of diamond is 4.2 and the velocity of light in air is 3.0 meters, stainless for 8 meters seconds calculate the velocity of light in diamond. So, how do we get the solution? Remember the refractive index is equivalent to velocity of light in medium one divided by velocity of light in medium two. So, repressing or substituting it appropriately you will get that the refractive index which is 2.42 is given by velocity of right in air divided by velocity of right in medium two. So, this gives us a ratio that by computing appropriately making V to the subject of the formula it gives us a velocity of 1.24 times stainless for 8 meters per second. So, what about in successive media that is light moving from one medium to another and in each at every interface there is bending which occurs how do we get to know the refractive index. So, sin r all of a sin r is equal to the refractive index of medium one with respect to medium two. So, at the second interface our angle of refraction becomes the angle of incidence and the angle of refraction takes after the interface in medium two gives us refraction angle at the angle of refraction in medium three. So, this gives us the angle of incidence which is the angle of refraction in medium one with respect with respect to medium three giving us equation three. So, by computing this you will realize that we have a successful way of getting the refractive index throughout the medium given for instance since here we have three medium. So, the refractive index of medium one with respect to medium three is given by the refractive index of medium one to medium two much by the refractive index of medium two to medium three and hence these equation holds etcetera. So, we can be able to determine a given number of refractive index through a given number of successive medium. So, let us see whether we got to understand the concept of this lesson calculate the angle between that the angle data bureau given that the refractive index of grass and water are three over two and four over three with respect to three from the diagram the angle of incidence is 30. You can refer these to physics students book three or give us a text through the numbers on your screen or visit our YouTube channel our Facebook page at RIMU TV or give us a tweet at RIMU TV underscore K E. So, once again I am your tutor stay tuned for more lessons to come.