Q. Which of the following elements of electrical engineering cannot be analyzed using Ohm’s law?
- A. Capacitors
- B. Inductors
- C. Transistors
- D. Resistance
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.
Q. What is constant for a charged spherical shell according to basic electrical energy?
- A. Electrical potential outside the spherical shell
- B. Electrical potential inside the spherical shell
- C. Electrical field outside the spherical shell
- D. Electrical field inside the spherical shell
Explanation: According to principles of electrical energy, the electrical potential inside the spherical shell is constant and is represented as V = kq/R where k = 1/4πεo. This potential is the same as that of the potential on the surface of the sphere.
Q. Where does electro-static shielding occur in a charged spherical shell?
- A. When electrical potential outside spherical shell is zero
- B. When electrical potential inside the spherical shell is zero
- C. When electrical field outside the spherical shell
- D. Electrical field inside the spherical shell
Explanation: The electrical field inside the spherical shell is zero and this is basically known as electrostatic shielding. The electric field outside the sphere is inversely proportional to the square of the radius.
Q. Which of the following is a correct representation of peak value in an AC Circuit?
- A. RMS value/Peak factor
- B. RMS value*Form factor
- C. RMS value/Form factor
- D. RMS value*Peak factor
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.
Q. Which of the following according to fundaments of electrical energy is correct about alternating current?
- A. Frequency is zero
- B. Magnitude changes with time
- C. Can be transported to larger distances with less loss in power
- D. Flows in both directions
Explanation: An alternating current changes its value with time and flows in both directions. The loss in power is less due to alternating current properties and thus, can be transported to larger distances.
Q. How many cycles will an AC signal make in 2 seconds if its frequency is 100 Hz?
- A. 50
- B. 100
- C. 150
- D. 200
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.
Q. What will be the direction of the drift velocity of electrons change with respect to the electric field?
- A. same as that of electric field
- B. opposite to that of electric field
- C. perpendicular to that of the electric field in a positive direction
- D. perpendicular to that of the electric field in a negative direction
Explanation: Basically drift velocity can be said to be the average velocity obtained by the free electrons in metal when an electric field is applied. The direction of drift velocity for the electrons present in metal will be opposite to that of the applied electric field.
Q. What will be the current density of metal if a current of 30A is passed through a cross-sectional area of 0.5m2?
- A. 7.5 A/m2
- B. 15 A/m2
- C. 60 A/m2
- D. 120 A/m2
Explanation: Current density is the ratio of the current flowing in a cross-sectional area. If a current of 30A is passed through a cross-sectional area of 0.5m2.
Q. 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?
- A. R1 will consume more power
- B. R2 will consume more power
- C. R1 and R2 will consume the same power
- D. The relationship between the power consumed cannot be established
Explanation: In the electrical engineering introduction 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.
Q. What is zero for a charged spherical shell?
- A. Electrical potential outside the spherical shell
- B. Electrical potential inside the spherical shell
- C. Electrical field outside the spherical shell
- D. Electrical field inside the spherical shell
Explanation: According to the fundamentals of the electrical field inside the spherical shell is zero and this is known as electrostatic shielding. The electric field outside the sphere is inversely proportional to the square of the radius.
Q. What kind of quantity is an Electric potential?
- A. Vector quantity
- B. Tensor quantity
- C. Scalar quantity
- D. Dimensionless quantity
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.
Q. What do crowded lines of force indicate?
- A. Strong electric field
- B. Weak electric field
- C. Strong electric potential
- D. Weak electric potential
Explanation: According to the principles of electric fields, when crowded lines of field are present the electric fields are very strong. The strong electric field can be witnessed near the poles of a magnet as the lines of force are crowded in this region.
Q. What is the direction of the electric field at a point?
- A. Along the line perpendicular to the electric field
- B. Along the line tangent to the electric field
- C. Electric field has no direction
- D. Electric field has a random direction
Explanation: According to the basics of the Electric field, it is a vector quantity and has a direction. The direction of the electric field is said to be along the line tangent to the electric field.
Q. What is the magnitude of mutually induced emf, E2 in a transformer?
- A. directly proportional to rate of change of flux and number of secondary turns
- B. inversely proportional to rate of change of flux and number of secondary turns
- C. proportional to rate of change of flux and inversely proportional to number of secondary turns
- D. inversely proportional to the rate of change of flux and proportional to number of secondary turns
Explanation: Due to the supply voltage, a secondary induced emf is produced. V1 is in antiphase with E2 and the magnitude of E2 is proportional to rate of change of flux and number of secondary turns.
Q. Which of the following will happen in a transformer when the number of secondary turns is less 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
Explanation: The voltage transformation ratio is basically the ratio of the number of secondary turns to that of the number of primary turns. When the transformation ratio is less than 1, the step-down operation occurs.
Q. What is the number of primary turns in a 200/1000 V transformer if the emf per turn is 10V?
Explanation: The number of primary turns is the ratio of induced emf in the primary to the emf induced per turn. Thus, the number of primary turns in a 200/1000 V transformer with emf per turn of 10V is 200/10 = 20.
Q. Which of the following is a correct representation of average value in an AC Circuit?
- A. RMS value/Form factor
- B. RMS value*Form factor
- C. RMS value/Peak factor
- D. RMS value*Peak factor
Explanation: The form factor basically gives the expression for DC of equal power to a given AC. A form factor in an AC circuit represents the ratio of the RMS value to the average value. Thus, average value = RMS value/Form factor.
Q. Who defined electric current and devised a method to measure current?
- A. Michael Faraday
- B. Andre-Marie Ampere
- C. Nikola Tesla
- D. Alessandro Antonio Volta
Explanation: Andre-Marie Ampere is a French physicist and mathematician who defined electric current and devised a method to measure current in the 1820s.
Q. How many electrons will constitute 2 Coulombs of electric charge?
- A. 6.24 * 1018 electrons
- B. 12.48 * 1018 electrons
- C. 1.602 * 1019 electrons
- D. 3.204 * 1019 electrons
Explanation: One Coulomb of charge consists of 1/(1.602*10-19) electron that is 6.24 * 1018 electrons. A coulomb is a unit for the charge. Thus, for 2 Coulombs of charge will have 6.24 * 1018 * 2 = 12.48 * 1018 electrons.
Q. Which of the following is correct about direct current?
- A. Magnitude is constant
- B. Frequency is zero
- C. Can be transported to larger distances with less loss in power
- D. Flows in one direction
Explanation: A direct current has a fixed value and does not change with time. The frequency of the direct current is equal to zero as it does not change with time.
Q. Who witnessed the effect of magnetism for the first time?
- A. Hans Christian Orsted
- B. Alexander Graham Bell
- C. Michael Faraday
- D. Gustav Robert Kirchhoff
Explanation: Hans Christian Orsted was a Danish physicist and chemist who witnessed the effect of magnetism for the first time. He discovered that electric current can create a magnetic field using an experiment.
Q. Which of the following according is correct about electrical conductivity?
- A. It is the ratio of current density to the electric field
- B. It is the product of current density and electric field
- C. It is the ratio of the electric field to current density
- D. It is the reciprocal of the product of current density and electric field
Explanation: Electrical conductivity gives the ability of a conductor to conduct electric current. The point form of Ohm’s law says that the electrical conductivity (σ) is the ratio of current density (J) to electric field (E).
Q. What is responsible for the current to flow?
- A. Protons
- B. Electrons
- C. Nucleus
- D. Protons and Electrons
Explanation: For the current to flow in a circuit electrons are required. Electrons are negatively charged and when the potential difference is applied these electrons flow to constitute a current. The current direction is opposite to the electron flow.
Q. Which of the following according to KCL must be zero?
- A. Algebraic sum of currents in closed-loop
- B. Algebraic sum of power in closed-loop
- C. Algebraic sum of currents entering and leaving a junction
- D. Algebraic sum of voltages across the input and output
Explanation: KCL or Kirchhoff’s current law helps in finding the currents flowing in the circuit. KCL states that the current entering a junction is equal to the current leaving a junction.
Q. How many directions can the electric field at a point have?
- A. Zero
- B. One
- C. Two
- D. Many
Explanation: Electric field is a vector quantity and has a direction. The direction of the electric field is said to be along the line tangent to the electric field. Thus, the electric field at a point has one direction.
Q. 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
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.
Q. Which of the following is correct about the voltage transformation ratio in electrical engineering?
- A. Ratio of number of primary turns to the number of secondary turns
- B. Ratio of induced emf in secondary to induced emf in primary
- C. Ratio of secondary current to the primary current
- D. Ratio of power in primary to power in secondary
Explanation: The voltage transformation ratio is the ratio of the number of secondary turns to the number of primary turns. This can also be expressed as the ratio of induced emf in secondary to induced emf in primary or ratio of primary current to secondary current.
Q. Which of the following according to the fundamentals of electrical engineering is correct about the induced emf in primary of transformer?
- A. It is the ratio of primary turns to emf induced per turn
- B. It is the product of primary turns and emf induced per turn
- C. It is the ratio of secondary turns to emf induced per turn
- D. It is the product of secondary turns and emf induced per turn
Explanation: The number of primary turns is the ratio of induced emf in the primary to the emf induced per turn. Thus, the induced emf in the primary of the transformer is the product of primary turns and emf induced per turn.
Q. 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
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.
Q. What does positive power in an electrical element indicate?
- A. Element is absorbing power
- B. Element is supplying power
- C. Element may absorb or supply power
- D. Element is neither absorbing nor supplying power
Explanation: Power in an electrical element is the product of voltage and current. Positive power will be established when both voltage and current are positive or both are negative. Positive power will indicate that the element is absorbing power.
Q. How does induce emf in DC motor react to supply voltage?
- A. It will aid the supply voltage
- B. It will be double the supply voltage
- C. It will oppose the supply voltage
- D. It will be half of the supply voltage
Explanation: Lenz’s law suggests that the direction of induced emf is such that it opposes the cause. The supply voltage will be the cause in this case. Thus induced emf will oppose the supply voltage.
Q. Which of the following type of circuits in electrical engineering cannot be analyzed using Ohm’s law?
- A. Unilateral
- B. Bilateral
- C. Linear
- D. Conductors
Explanation: Ohm’s law cannot be used for analyzing unilateral networks as such networks only allow current flow in one direction. A unilateral network can consist diode, transistor, etc.
Q. Which of the following according to KVL must be zero?
- A. Algebraic sum of currents in closed-loop
- B. Algebraic sum of power in closed-loop
- C. Algebraic sum of losses in closed-loop
- D. Algebraic sum of voltages in closed-loop
Explanation: KVL or Kirchhoff’s voltage law proves the law of conservation of energy around a closed path. KVL can be used in the circuit to find the circuit parameters by considering that the algebraic sum of voltages in a closed loop is zero.
