A judgement or an observation?
This is the Conservation of energy. We say energy is conserved because none is lost in the process.
There would be no light at night foe nocturnal animals
Answer:
Telegraph distance will be 9.6 mile
Explanation:
We have given the voltage V = 9 volt
Contact resistance = 4 ohm
Relay resistance = 80 ohm
And wire has a resistance = 10 ohm/mile
We have given the current = 50 mA =0.05 A
According to ohm's law 
So the resistance of wire = 180-4-80=96 ohm
So the length of the telegraph distance will be
Answer:
Part a)

Part b)

Explanation:
Part a)
Proton is released from one plate and strike at other plate in time


now we will have



now we know that



Part b)
Speed of the proton when it strike the other plate can be calculated by kinematics equations


