Questions in Electromagnetic Waves

Select	Question
	For skywave propagation of a 10 MHz signal, what should be the minimum electron density in ionosphere
	The pressure exerted by an electromagnetic wave of intensity I (watts/m2) on a nonreflecting surface is [c is the velocity of light]
	Infrared radiation was discovered in 1800 by
	Which of the following is electromagnetic wave
	Which one of the following is not electromagnetic in nature
	Light wave is travelling along y-direction. If the corresponding $\vec E$ vector at any time is along the x-axis, the direction of $\vec B$ vector at that time is along
	If c is the speed of electromagnetic waves in vacuum, its speed in a medium of dielectric constant K and relative permeability ${\mu _r}$ is