Recent content by mehrdad_baghery

I am highly curious about how did 17th century scientists like Fresnel, Fraunhofer, etc. made optical equipment such as gratings, pinholes, etc.?

Thanx, but it seems that I couldn't explain what I meant. Let me explain with attached picture (pls. see it). In halliday book the 1st picture is used for deriving the speed of a wave, he has considered the specified two tensions (which are shown with F) to be equal. The 2nd picture has been...

Every point in a wave is moving, so it is not stationary, as a result the tension is not same at different points. so why does halliday have considered the tension in a wave same for calculating the wave speed?

In halliday physics book when we are going to derive the speed or the equation of a wave we consider the tension of the string to be same along the string, but when we are going to derive the energy transferred by the string we consider the tension to be maximum in nodes and minimum in...