1. In D.C. generators, the brushes remain in contact with conductors which ?

lie under south pole

lie under north pole

lie in the inter-polar gaps

Bone of the above

Answer: lie in the inter-polar gaps

Explanation:


2. Armature reaction in a generator results in ?

demagnetisation of leading pole tip and magnetisation of trailing pole tip

demagnetisation of trailing pole tip and magnetisation of leading pole tip

dimagnetising the centre of all poles

magnetising the centre of all poles

Answer: demagnetisation of leading pole tip and magnetisation of trailing pole tip

Explanation:


3. In a DC generator the number of mechanical degrees and electrical degrees will be the same when ?

r.p.m. is more than 300

r.p.m, is less than 300

number of poles is 4

number of poles is 2

Answer: number of poles is 2

Explanation:


4. The material for commutator brushes is generally ?

mica

copper

cast iron

carbon

Answer: carbon

Explanation:


5. In a D.C. generator, the armature reaction results in ?

demagnetisation of the centres of poles

magnetisation of inter poles

demagnetisation of the leading pole tip and magnetisation of the trailing pole tip

magnetisation of the leading tip and demagnetisation of the trailing pole tip

Answer: demagnetisation of the leading pole tip and magnetisation of the trailing pole tip

Explanation:


6. The e.m.f. generated by a shunt wound D.C. generator is E. Now while pole flux remains constant, if the speed of the generator is doubled, the e.m.f. generated will be ?

E/2

2E

slightly less than E

E

Answer: 2E

Explanation:


7. In any rotating machine that part which houses the conductors and in which e.m.f. induced is to be utilised is called ?

rotor

stator

field

armature

Answer: armature

Explanation:


8. ln over compounded generator, full load terminal voltage is ?

almost zero

less than no-load terminal voltage

more than no-load terminal voltage

equal to no-Ioad terminal voltage

Answer: more than no-load terminal voltage

Explanation:


9. With a D.C. generator which of the following regulation is preferred ?

100% regulation

infinite regulation

50% regulation

1% regulation

Answer: 1% regulation

Explanation:


10. If residual magnetism of a shunt generator is destroyed accidentally, it may be restored by connecting its shunt field ?

in reverse

to a battery

to earth

to an alternator

Answer: to a battery

Explanation: