Is a tidal wave a mechanical wave or an electromagnetic wave? And why?

Which quantities are scalars? choose all that apply a. distance b. speed c. acceleration d. velocity

Light from a sodium lamp passes through a diffraction grating that has 1000 slits per millimeter. the interference pattern is viewed on a screen 1.000 m behind the grating. the first (m = 1) two bright yellow fringes that are visible are 0.7288 m and 0.7300 m from the central maximum. what are the wavelengths of these two fringes?

What is the name for the remnant of an asymptotic giant that has lost its shells? black dwarf white dwarf yellow giant black hole