MCQ’s on Basic 6 Electrical
Question 51
Which of the following will happen in a transformer when the number of secondary turns is greater than the number of primary turns?
(a) The voltage gets stepped up
(b) The voltage gets stepped down
(c) The power gets stepped up
(d) The power gets stepped down
The correct answer is (a) The voltage gets stepped up
Explanation: The voltage transformation ratio is the ratio of the number of secondary turns to that of the number of primary turns. When the transformation ratio is greater than 1, the step-up operation occurs.
Question 52
Insulators used on EHT transmission lines are made of
(a) PVC
(b) Porcelain
(c) Glass
(d) Stealite
The correct answer is (b) Porcelain
Question 53
What is the unit of current?
(a) Ampere
(b) Voltage
(c) Meter
(d) None of above
The correct answer is (a) Ampere
Question 54
The SI unit of electrical energy is?
(a) Watt-Second
(b) Joule
(c) KWh
(d) Volt-Ampere Second
The correct answer is (b) Joule
Explanation :- Joule is the SI Unit of Energy all others are the unit of Energy but not the SI Unit of energy.
Question 55
We have three resistances each of 1Ω,2Ω and 3Ω. If all the three resistances are to be connected in a circuit, how many different values of equivalent resistances are possible?
(a) Five
(b) Six
(c) Seven
(d) Eight
The correct answer is (d) Eight
Explanation
R1=1Ω,R2=1Ω R3=1Ω
1) R1, R2, R3 in series
2)R1, R2, R3 in parallel
3)R1,in series with parallel combination R2 &R3
4)R2,in series with parallel combination R1 &R3
5)R3,in series with parallel combination R1 &R2
6)R1,in parallel with series combination R2 &R3
7)R2,in parallel with series combination R1 &R3
8)R3,in parallel with series combination R2 &R1
Question 56
Electric pressure is also called
(a) resistance
(b) power
(c) voltage
(d) energy
The correct answer is (c) voltage
Question 57
Which of the following motors can be used to drive the rotary compressor?
(a) DC shunt motor
(b) DC series motor
(c) Universal motor
(d) Synchronous motor
The correct answer is (d) Synchronous motor
Explanation :- Rotary compressor generally demand constant speed operation throughout the load. Sometimes, DC machines are not able to produce constant speed throughout the process hence, synchronous machine is used.
Question 58
Which of the following current is drawn by the primary circuit of an ideal transformer when the secondary is open?
(a) Secondary current
(b) Leakage current
(c) Magnetizing current
(d) Working on current
The correct answer is (c) Magnetizing current
Explanation: When the secondary is open no current flows through the load, thus no secondary current is drawn. The primary coil for an ideal transformer is purely inductive and thus, only draws magnetizing current.