Physics
Electrical Machines and Circuits
754 Questions
Electrical machines and circuits involve the principles of alternating and direct current, transformers, diodes, and power consumption. These concepts are essential for engineering and technical exams. Review these practice questions to test your knowledge of circuit analysis.
Transformers and impedanceAlternating and direct currentCircuit components and diodesPower consumption calculations
Electrical Machines and Circuits Questions
-
rectifier
-
oscillator
-
voltage regulator
-
current limiter
C
Correct answer
Explanation
A Zener diode is specifically designed to operate in the reverse breakdown region, making it ideal for maintaining a constant voltage across a load.
-
current
-
resistance
-
power
-
voltage
-
wall clocks
-
digital multimeters
-
speed control of motors
-
All of the above
C
Correct answer
Explanation
Thyristors, such as SCRs, are widely used in power electronics for controlling the speed of motors by regulating the power delivered to them.
-
copper core
-
iron core
-
ferrite core
-
air core
C
Correct answer
Explanation
Pulse transformers require high-frequency performance and low eddy current losses. Ferrite cores are ideal for these applications due to their high electrical resistivity and high magnetic permeability at high frequencies.
-
Parallel to the conductor
-
In series with the conductor
-
a & b both
-
None of these
B
Correct answer
Explanation
To measure the current flowing through a conductor, an ammeter must be placed in series with the conductor so that the total current passes through the meter.
-
Parallel
-
Series
-
a & b both
-
None of these
A
Correct answer
Explanation
Parallel wiring is preferred for domestic appliances because it allows each device to operate independently at the same voltage and prevents the failure of one device from breaking the circuit for others.
-
Parallel
-
Random
-
Series
-
Positive and positive terminals
C
Correct answer
Explanation
Battery is a combination of two or more cells arranged in series.
-
Same potential
-
Difference in current
-
Difference in potential
-
Difference in temperature
C
Correct answer
Explanation
In an electric circuit, current flows due to potential difference.
-
Electrical appliances and circuits
-
Us from electric shock
-
Prevent the ammeter
-
Prevent the insulator
B
Correct answer
Explanation
A fuse wire prevents us from getting a shock as it melts down and breaks the circuit as soon as current larger than what is required flows through the circuit.
-
Sound
-
Remote control
-
Color balance
-
High voltage
-
None of these
B
Correct answer
Explanation
Some authorities are recommending TVs, VCRs and stereos be connected to power strips with switches turned off when not in use to save energy. Your remote will not work until power is switched back on.
C
Correct answer
Explanation
Electric meters measure the total energy consumed over time, which is expressed in kilowatt-hours (kWh). While watts measure power, the meter records the cumulative energy usage.
-
Conversion of DC to AC.
-
Regulation of fluctuation of voltage
-
Measurement of intensity flow of electricity
-
Conversion of low voltage into high voltage and vice versa
-
None
D
Correct answer
Explanation
A transformer is an electrical device that transfers electrical energy between two or more circuits through electromagnetic induction, typically used to increase or decrease voltage.
-
highest for 100 W bulb
-
highest for 60 W bulb
-
highest for 40 W bulb
-
same for all three bulbs
-
none of these
-
chokes low frequently currents
-
steps up the line voltage
-
reduces current in the circuit
-
steps down the line voltage
C
Correct answer
Explanation
A choke coil in a fluorescent tube circuit acts as an inductor that limits the current flowing through the tube, preventing it from drawing excessive current.
-
break the electrical circuit under strong current by melting
-
allow high current to flow without harm
-
regular electric shocks
-
save one from electric shocks
A
Correct answer
Explanation
A fuse wire is designed to have a low melting point. When excessive current flows, the wire heats up and melts, breaking the circuit to protect appliances from damage.