Basic Concept of Electricity MCQs

Question 1

Two coils having equal resistance but different inductances are connected in series. The time constant of the series combination is the

Accepted Answer

geometric mean of time constants of the individual coils

Answer

sum of time constant of the individual coils.

Answer

(d) product of the time constant of the individual coils.

Question 2

The cores in electrical machines are generally mode of laminations with a view to reduce

Accepted Answer

the eddy current loss

Answer

the hysteresis loss

Answer

the copper loss

Answer

eddy current, hysteresis and copper losses.

Question 3

Thermo-couple is based on

Accepted Answer

Seeback effect

Answer

Thomson

Answer

Joule's

Answer

None of these

Question 4

According to fuse law, the current carrying capacity varies as

Accepted Answer

(diameter)1.5

Answer

diameter

Answer

(diameter)14

Answer

diameter

Question 5

Lamps in street lighting are all connected in

Accepted Answer

parallel

Answer

series

Answer

series-parallel

Answer

end-to-end

Question 6

Resistance of earth should be

Accepted Answer

the minimum possible.

Answer

infinite

Answer

high

Answer

low

Question 7

When an electric current is passed trough a bucket full of water, lot of bubbling is there. The electric current is

Accepted Answer

dc

Answer

ac

Answer

pulsating

Answer

none of these

Question 8

Most important advantages of using electrical energy in the form of ac is

Accepted Answer

transformation of voltage is possible in case of ac only.

Answer

the construction cost per kw of ac generator is lower than that of dc generator

Answer

conductor of smaller x-section is required in case of ac in comparison to dc for carrying the same current.

Answer

less insulation is required in case of ac.

Question 9

An alternating current of frequency 50 Hz and maximum value 200 A given as

Accepted Answer

i = 200 sin 314 t.

Answer

i =200 sin 628 t.

Answer

i= 100 sin 314 t

Answer

i = 100 tri sin 157t