Tutor profile: Susomon D.
Subject: Physics (Waves and Optics)
what is the cause of refraction?
When light travels through a uniform medium it does not refract but when it is in a nonuniform medium it may refract because of the change of Phase rather you can say it is momentum. To conserve momentum Light refracted inside a nonuniform media, In your textbook, you can see they told about the velocity but in proper terminology of refraction, you must say its momentum conservation.
Subject: Physics (Thermodynamics)
Imagine, You are walking on an ice road, and you are slipped down due to your footstep, Do you know why you slipped down on the icy ground?
I know what kind of answer comes to your mind, lack of frictional energy right? It is not a wrong guess but not absolutely true also when hitting the ice with your feet you can see that the top surface of the ice melting down and makes the road a little bit slippery now you may ask yourself when the weather temperature is -10deg so how the ice melts here, It's due to your energy when you hitting the surface, you pushing the surface of the road by your feet according to newton's law you may remember that surface also push you upward due to its reaction principle that means ice do some work and it loses its energy, from where the energy comes, my dear, it is an internal energy that is stored named as latent heat in ice. so you fell down on the ice road because of the melting of ice down to your feet which reduces the frictional energy under the area of the feet.
Have you ever observe that when you slowed down the water flow in the kitchen tap, the trajectory goes thinner as it goes down towards the ground, do you know why this happens?
It is because of the variation of velocity, as the water molecule comes down it gathers more kinetic energy in it so its velocity will increase. you know that for a fluid motion velocity is inversely proportional to the cross-sectional area so when the velocity of water increases, cross-sectional area decreases which means the waterline (streamline) goes thinner and thinner.
needs and Susomon will reply soon.