Answer:
The human retina can only detect incident light that falls in waves 400 to 720 nanometers long, so we can't see microwave or ultraviolet wavelengths. This also applies to infrared lights which has wavelengths longer than visible and shorter than microwaves, thus being invisible to the human eye.
Teacher -> teach the topic
Learner -> learn the topic
Is that what you’re asking?
Answer:
It depends on how you use the spoon...
if you are keeping one end of the spoon and pressing other end, the force you provide is supported by the force due to gravity... Hence it is easy to open this way :)
F + G ... Where F is the force you provide and G is the force due to gravity.
answer: transverse and longitudinal
