State the assumptions on which a PP curve is based. Also explain its properties. Use diagrame

What are the two assumptions on which Huygens' principle is based? Explain Huygen's geometrical construction for the wavefronts.

Which position for hydrogen explain all its properties ?

Which position for hydrogen explain all its properties ?

Which position for hydrogen explain all its properties ?

State the basic assumption on which the kinetic theory of gases is based.

Identify the given diagram of microbes and also explain its role.