Which is part of an ac generator?

armature

transformer

commutator

turbine

Armature is part of an AC generator

Option A  

Explanation:  

Armature that revolves between two poles of magnet in an ac generator and plays a prime role in converting mechanical energy into electrical. An AC generator works on the principles of electromagnetic induction.  

When the armature rotates in between two magnets facing each other with opposite polarities, it rotates on the axis which is perpendicular to the magnetic field's direction.

With this, an electromotive force (emf) is induced in the armature and thus, the electric current flows through the rings to the wires and we get an ac current. Hence, the prime role in producing the ac current in the generator is done by the armature and its rotatory motion.

one person pulls 90n one way and the other has 100n pulling the other way.

so the net force = 90 - 100 = -10n,

or the ans can be 10n if the picture shows -90n and 100n instead.

it is b. absorbs thermal energy