Is it time for the traditional 1kHz tone test for amp power to go? (brief Amir name drop)

A typical red laser pointer has a wavelength of 650 nm . Suppose we wanted to test the wave nature of light by carefully cutting two parallel slits in a dark plastic sheet. We would then shine the laser through the slits onto a wall located 1  m beyond the sheet. (a) Determine the slit spacing needed so that the bright spots on the wall would be discernible with 1  cm spacing. (b) Is this a feasible "home experiment"? Is it possible to cut slits with that separation using typical household tools

Hilary Barry - One of the most irritating sounds in a tv...

20khz数字超声波焊接发生器换能器模具，用于面膜机非织造穿孔组件

20 Khz Ultrasonic Generator