Answer:
Tyndall effect: The phenomenon of
scattering of light by colloidal particles
gives rise to Tyndall effect.
<u>Examples</u> :
1. Tyndall effect can be observed
when sunlight passes through a canopy of a dense forest, then the
path of light becomes visible.
2. The visible beam of headlight in fog.
3. When a beam of light enters a
smoke filled room through a small
hole, then path of light becomes
visible.
Answer: D) purposive sampling
Explanation: Since there is no list of people and there is no reason to believe that they know each other, the researcher will need to get all possible cases that fit his research using various methods. This is known as purposive sampling.
It is a non-random sampling used in situations in which an expert uses judgment in selecting cases with a specific purpose in mind. Here, researcher uses wide range of methods to locate all possible cases of a highly specific and difficult-to-reach population.
