d = distance between the two point charges = 60 cm = 0.60 m
r = distance of the location of point "a" where the electric field is zero from charge
between the two charges.
= magnitude of charge on one charge
= magnitude of charge on other charge
= 3 
= Electric field by charge
at point "a"
= Electric field by charge
at point "a"
Electric field by charge
at point "a" is given as
= k
/r²
Electric field by charge
at point "a" is given as
= k
/(d-r)²
For the electric field to be zero at point "a"
=
k
/(d-r)² = k
/r²
/(d-r)² = 3
/r²
1/(0.60 - r)² = 3 /r²
r = 0.38 m
r = 38 cm
Windmills run on the principle of mechanical energy and work. Moving air (wind) possesses some amount of energy in the form of kinetic energy (due to motion). This energy gives the air the ability to do work on the blades of the fan.
Answer: 77 degrees
Explanation:
According to the Law of Reflection, when a ray of light strikes a surface, the angle of this ray (incident ray) with respect to the normal of the surface is equal to the angle that forms the reflected ray with the same normal of the surface.
In other words:
Both the incident ray and the reflected ray and the normal to the surface are in the same plane, in addition, the angle of the incident ray is equal to the angle of the reflected ray.
In this context, if the angle of incidence is 77 degrees, the angle of reflection is 77 degrees, as well.