A) experimental because he isn’t sure and is testing out
Through the medium of electromagnetism, energy from waves get transferred which a hydroelectric power plant heavily rely on. The turbine eventually converts the energy from the waves into mechanical energy which is transformed to electrical energy using a generator.
Based on this, you can tell that Iron(Fe) does not react with Nitrogen(N), but does with something in normal air. The element the Iron is reacting with Oxygen(O), and the compound that is formed is called iron oxide.
Answer: 
Explanation:
Given
Wavelength of light 
Screen is
away
Distance between two adjacent bright fringe is 
When same experiment done in water, wavelength reduce to 
So, the distance between the two adjacent bright fringe is 
Keeping other factor same, distance becomes
