zeroth law of thermodynamics

first law of thermodynamics

second law of thermodynamics

third law of thermodynamics

X-rays

Microwaves

Radiowaves

Sound waves

Human eye is a refracting system containing a diverging lens.

The retina of the human eye contains millions of light sensitive cells, called rods and cones, which convert the light into electrical messages.

Every image that is focused on the retina is upside down.

We need both eyes to judge the relative positions of objects accurtely.

Ultrasonic waves cannot get reflected, refracted or absorbed.

Ultrasonic waves are used to detect the presence of defects like cracks, porsity, etc. in the internal structure of common structure materials.

ultrasonic waves can be used for making holes in very hard materials like diamond.

Ultrasonic waves cannot travel through vacuum.