Answer:
Electromagnetic cranes are used to separate copper from iron in a scrap yard. The current is switched on to energies the electromagnet and pick up the iron pieces from the scrap. Then these iron pieces are moved to another position, the electromagnet in switched off and the iron pieces are released.
Explanation:
Answer:
D.
Explanation:
To solve the problem it is necessary to apply the concepts of Destructive and constructive interference. The constructive interference in tin film is given by

Where,
t = thickness
Wavelenght
m= is an integer
n= film/refractive index
We use this equaton because phase change is only present for gasoline air interface, but not at the gasoline-water interface. <em>The minimum t only would be when the value of m=0 then</em>



Therefore the correct answer is D. The minimum thickness of the film to see ab right reflection is 100nm
Answer:
A force pump can be used to raise water by a height of more than 10m, the maximum height allowed by atmospheric pressure using a common lift pump.
In a force pump, the upstroke of the piston draws water, through an inlet valve, into the cylinder. On the downstroke, the water is discharged, through an outlet valve, into the outlet pipe.