Month: January 2022

Basic Electrical MCQ

Basic Electrical / By
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1. With the rise in temperature the resistance of carbon

  1. decreases
  2. increases
  3. remain constant
  4. none of the above

Answer: 1

2. When number of capacitors are connected in series, then the equivalent capacitance is

  1. increases
  2. decreases
  3. remain same
  4. none of the above

Answer: 2

3. Which of the following elements of electrical engineering cannot be analyzed using Ohm’s law?

  1. Capacitors
  2. Inductors
  3. Transistors
  4. Resistance

Answer: 3
Explanation: Ohm’s law cannot be used for unilateral networks as such networks only allow current flow in one direction. Transistor forms a unilateral network. Thus, Ohm’s law cannot be used on Transistors.

4. According to the fundamentals of electrical engineering, which of these is a correct representation of peak value in an AC Circuit?

  1. RMS value/Peak factor
  2. RMS value*Form factor
  3. RMS value/Form factor
  4. RMS value*Peak factor

Answer: 4
Explanation: A peak factor in an AC circuit represents the ratio of the peak value to the RMS value. The peak factor also called the crest factor indicates how extreme the peaks are present in a waveform.

5. How many cycles will an AC signal make in 2 seconds if its frequency is 100 Hz?

  1. 200
  2. 150
  3. 100
  4. 50

Answer: 1
Explanation: In electrical engineering, the frequency represents the ratio of the number of cycles to the total time. Since frequency is given as 100 Hz and the time is 2 sec thus a total of 200 cycles will be made.

6. Which of the following is correct about the power consumed by R1 and R2 connected in series if the value of R1 is greater than R2?

  1. R1 will consume more power
  2. R2 will consume more power
  3. R1 and R2 will consume the same power
  4. The relationship between the power consumed cannot be established

Answer: 1
Explanation: In the introduction to electrical engineering it is explained that the power can be expressed as P = I2*R. When two resistors are connected in series the current flowing through the resistors is the same and thus, power consumed by the larger resistor will be more.

7. What kind of quantity is an Electric potential?

  1. Dimensionless quantity
  2. Tensor quantity
  3. Vector quantity
  4. Scalar quantity

Answer: 4
Explanation: Electric potential refers to the work done to bring a unit positive charge from a point with higher potential to a point with lower potential. Since electric potential only has magnitude but no direction, it is a scalar quantity.

8. Who defined electric current and devised a method to measure current?

  1. Andre-Marie Ampere
  2. Nikola Tesla
  3. Alessandro Antonio Volta
  4. Michael Faraday

Answer: 1
Explanation: Andre-Marie Ampere is a French physicist and mathematician who defined electric current and devised a method to measure current in the 1820s.

9. An inductor is a device which store energy in the form of

  1. magnetic field
  2. electric field.
  3. both electric and magnetic field.
  4. voltage and current.

Answer: 1

10. A capacitor is a device designed to store energy in the

  1. magnetic field
  2. electric field.
  3. both electric and magnetic field.
  4. plates

Answer: 2

Transformer Overview

Electrical Machines / By

What is Transformer?

Transformer is an AC machine that transfers electrical energy from one electrical circuit to another. Since there is no moving part in Transformer, it is also called Static device. Due to its static nature it requires minimum amount of repair and maintenance.


Types of Transformer

(1) Step-up Transformer:- When Output Voltage of a  Transformer is higher than its input Voltage, it is called step up transformer. Such transformer’s are used at Power stations where generating voltage i.e. 11 KV is raised to higher levels i.e. 66/132/220/400 KV for transmission purpose to Sub-stations.

(2) Step Down Transformer:- When Output Voltage of a Transformer is lower than its input Voltage, it is called step down transformer. Such Transformer’s are used at Sub-stations to lower down voltage from 66/132/220/400 KV to 33KV and 11 KV for distribution to various Industrial Consumer’s and also Distribution Transformer’s to fed house hold consumers. 

(3) Distribution Transformer:- These type of Transformer is used to convert 11KV voltage level to 440V which is used by House-hold various commercial consumers like shops, Panchayat ghar’s etc. Distribution Transformers are mostly seen at vicinity of house-hold consumers installed over H type structure. Since it converts HT voltage to LT voltage so these are used at nearby consumer’s to eliminate voltage drops