What is the relationship between power, voltage, and current in a DC circuit?
A \( P = V/I \)
B \( P = VI \)
C \( P = I^2V \)
D \( P = V^2I \)
In a DC circuit, power (\( P \)) is the product of voltage (\( V \)) and current (\( I \)). This is the fundamental formula for electrical power.
What happens to the total capacitance when capacitors are connected in parallel?
A It increases
B It decreases
C It remains constant
D It becomes zero
The total capacitance in a parallel connection is the sum of individual capacitances: \( C_{\text{total}} = C_1 + C_2 + \dots \).
What is the primary advantage of an AC system over a DC system for power transmission?
A Lower voltage
B Easier to convert voltages using transformers
C No energy loss
D Constant current flow
AC systems allow easy voltage transformation using transformers, reducing transmission losses over long distances.
Which of the following is a non-ohmic device?
A Copper wire
B Resistor
C Filament bulb
D Aluminum wire
The filament bulb is non-ohmic because its resistance changes with temperature, causing a nonlinear relationship between voltage and current.
What is the unit of electric charge?
A Joule
B Ampere
C Coulomb
D Watt
Electric charge is measured in coulombs (C), where 1 coulomb equals the charge transported by a current of 1 ampere in 1 second.
What is the effect of temperature on the resistance of a semiconductor?
A Resistance increases with temperature
B Resistance decreases with temperature
C Resistance remains constant
D Resistance becomes infinite
In semiconductors, increasing temperature provides more energy for charge carriers, reducing resistance.
Which device is used to measure the frequency of an AC signal?
A Voltmeter
B Ammeter
C Oscilloscope
D Ohmmeter
An oscilloscope can measure the frequency of an AC signal by analyzing the waveform displayed on its screen.
What type of loss occurs in a transformer due to the repeated magnetization and demagnetization of the core?
A Copper loss
B Eddy current loss
C Hysteresis loss
D Dielectric loss
Hysteresis loss occurs in the transformer core due to repeated cycles of magnetization and demagnetization, which consume energy.
What is the role of a load in an electrical circuit?
A To store energy
B To consume power
C To increase current
D To generate voltage
A load, such as a light bulb or motor, consumes electrical power to perform work or produce heat, light, or motion.
What is the relationship between magnetic flux density (\( B \)) and magnetic field strength (\( H \)) in a material?
A \( B = H/I \)
B \( B = \mu H \)
C \( B = H \times \mu_0 \)
D \( B = I \times H \)
Magnetic flux density (\( B \)) is the product of magnetic field strength (\( H \)) and the material’s permeability (\( \mu \)).
Which device is used to test the polarity of a DC circuit?
A Ammeter
B Test lamp
C Multimeter
D Voltmeter
A multimeter can measure voltage and indicate the polarity of a DC circuit by showing the direction of current flow.
What is the primary purpose of grounding in electrical systems?
A To increase voltage
B To protect devices from surges and shocks
C To amplify current
D To reduce resistance
Grounding provides a safe path for fault currents to flow into the Earth, preventing damage to devices and reducing the risk of electric shocks.
What is the typical range of power factor in industrial applications?
A 0.1 to 0.5
B 0.5 to 1.0
C -1.0 to 0
D 0 to 0.2
Industrial systems typically operate within a power factor range of 0.5 to 1.0, with higher values indicating more efficient power usage.
Which type of transformer winding is connected to the load?
A Primary winding
B Secondary winding
C Tertiary winding
D Core winding
The secondary winding of a transformer is connected to the load and delivers the output voltage.
What is the effect of increasing the number of turns in a solenoid?
A Decreases magnetic field strength
B Increases magnetic field strength
C Reduces current
D Increases resistance
Increasing the number of turns in a solenoid enhances the magnetic field strength, as \( B \propto N \), where \( N \) is the number of turns.
What is the frequency of AC supply in India?
A 50 Hz
B 60 Hz
C 100 Hz
D 25 Hz
The standard frequency of AC supply in India is 50 Hz, meaning the current completes 50 cycles per second.
What is the purpose of a relay in electrical circuits?
A To measure current
B To amplify voltage
C To control a circuit remotely
D To reduce resistance
A relay uses a small electrical signal to control the operation of a larger electrical circuit, providing isolation and remote switching.
What is the SI unit of inductance?
A Henry
B Weber
C Tesla
D Joule
Inductance is measured in henries (H), where one henry is the inductance that produces one volt when the current changes at one ampere per second.
Which property of a conductor determines its ability to resist current flow?
A Conductivity
B Permeability
C Resistivity
D Dielectric strength
Resistivity (\( \rho \)) is a material property that determines how strongly it resists current flow. It depends on the material’s composition.
What is the primary function of a rheostat?
A To increase resistance
B To adjust current flow
C To reduce voltage
D To step down power
A rheostat is a variable resistor that controls the current flow in a circuit by changing its resistance.