Answer:
Explanation:
Pinhole camera is a simple camera. It does not have a lens. The light passes from a hole and an inverted image is formed on the opposite side of the box.
If there are two equal and opposite forces on the SAME THING, then the thing doesn't accelerate. You're right about that. But the action and reaction forces act on two different things. The bullet and the rifle. The ball and the bat. The airplane and the air. etc. So BOTH can accelerate.
Answer: 
Explanation:
Given
Capacitance 
Resistance 
Inductance 
In LCR circuit, current is maximum at resonance frequency i.e.

Insert the values

Also, frequency is given by


Commutator is an attachment, connected to the armature of motor or generator through which electrical connection is made and ensures that the current is flowing like a direct current
And it is a device for reversing the direction of flow of electrical current.
In addition by using induction the current is induced in a circuit due to a change or motion in a magnetic field is so directed as to oppose the change in flux "is the surface magnetic divided by time" and to exert a mechanical force opposing the motion of the spin of wire coil.