Give one use each of (a) microwaves , (b) ultraviolet radiations , (c) infrared radiations, and (d) gamma rays.
The threshold wavelength for photoelectric emission from a material is 5200˙A. Photoelectrons will be emitted when this material is illuminated with monochromatic radiation from a
State one harmful effect each of the (a) ultraviolet and (b) infrared radiations.