Options (b) and (d) are correct about an electric motor.
An electric motor is a device which coverts electrical energy into mechanical energy.It works on the principle that when a current carrying coil is placed in a magnetic field, it experiences torque. Because of that torque, the coil rotates and thus the electrical energy gets converted into mechanical (motion) energy.
Wind farms, solar collectors, and nuclear power plants generate no pollution.
But wind farms make noise, wind and solar are both hazardous to birds, and there's no known means of disposing of nuclear plant waste that's completely safe.
Answer:
Minimum thickness will be 100 nm
Explanation:
We have given refractive index is n = 1.5
Wavelength of the light incidence 
= 600 nm
We have to find the smallest thickness of the film so that there will be minimum light reflect
For minimum thickness of non reflecting film
, here t is thickness, is wavelength and n is refractive index
Putting all values 
So minimum thickness will be 100 nm
I think you forgot to give the choices along with the question. I am answering the question based on my research and knowledge. <span>If a layer was deposited but does not appear in the rock record, the thing that happened is erosion. I hope that this is the ans wer that has actually come to your desired help.</span>
