1.
When two loops with or without contacts between them affect eachother through the magnetic field generated by one of them, they aresaid to be magnetically coupled.
Correct Answer
A. True
Explanation
When two loops, whether they have contacts between them or not, influence each other through the magnetic field produced by one of the loops, they are considered to be magnetically coupled. This means that changes in one loop's magnetic field can induce a current or voltage in the other loop. The statement is correct in stating that when this magnetic interaction occurs between the loops, they are magnetically coupled.
2.
The resonant circuit consists only of a capacitor with a voltage or current source.
Correct Answer
B. False
Explanation
The given statement is false. A resonant circuit consists of both an inductor and a capacitor, along with a voltage or current source. The inductor and capacitor work together to create a resonant frequency at which the circuit can store and exchange energy efficiently. Without the presence of an inductor, the circuit would not exhibit resonance.
3.
This curve is for bandstop filter
Correct Answer
B. False
Explanation
The given statement is false. The curve is not for a bandstop filter.
4.
The resonant circuit consists only of inductor with a voltage or current source.
Correct Answer
B. False
Explanation
The resonant circuit does not consist only of an inductor with a voltage or current source. A resonant circuit typically consists of an inductor and a capacitor connected in parallel or in series. This combination of components creates a circuit that can resonate at a specific frequency, allowing for efficient transfer of energy between the inductor and capacitor. Therefore, the statement is false.
5.
This curve indicates that power willbe a maximum at fr and varying thefrequency in either direction resultsin a rise of the power.
Correct Answer
B. False
Explanation
The statement is false because the curve indicates that power will be a maximum at fr, but varying the frequency in either direction will result in a decrease in power rather than a rise.
6.
The value of ω that satisfies this condition is called the resonant frequency
Correct Answer
B. False
Explanation
The given statement suggests that the value of ω that satisfies a certain condition is called the resonant frequency. However, the correct answer is False. This means that the statement is incorrect and the value of ω that satisfies the condition is not called the resonant frequency.
7.
The bandwidth is the average between the half power points on the response curve of the filter.
Correct Answer
B. False
Explanation
The correct answer is False. The bandwidth of a filter is not the average between the half power points on the response curve. Instead, it is typically defined as the range of frequencies where the filter's response is within a certain percentage (e.g., 3dB) of the maximum response. The half power points, on the other hand, refer to the frequencies where the filter's response is reduced by half of the maximum power.
8.
The total impedance of RLC parallel circuit is given in the shown relation
Correct Answer
B. False
Explanation
The given statement is false. The total impedance of an RLC parallel circuit is not provided in the shown relation. The total impedance in a parallel RLC circuit is calculated by taking the reciprocal of the sum of the reciprocals of the individual impedances.
9.
The phase of The current across coil in series resonant circuit is +90 when the supply is 5Sinωt
Correct Answer
B. False
Explanation
In a series resonant circuit, the phase of the current across the coil is not +90 when the supply is 5Sinωt. The phase depends on the frequency of the supply and the values of the inductance and capacitance in the circuit. Therefore, the statement is false.
10.
In RLC series resonance the Magnitude of inductive reactance must Eliminates the Magnitude of capacitive reactance to result a pure inductor
Correct Answer
B. False
Explanation
In RLC series resonance, the magnitude of inductive reactance does not need to eliminate the magnitude of capacitive reactance to result in a pure inductor. In fact, in RLC series resonance, the magnitude of inductive reactance is equal to the magnitude of capacitive reactance, resulting in a purely resistive circuit. Therefore, the given statement is false.
11.
Since the current is maximum at resonance,it follows that the power must similarly be maximum at resonance.
Correct Answer
A. True
Explanation
At resonance, the impedance of a circuit is at its minimum, which means that the current flowing through the circuit is maximum. According to the power formula (P = I^2 * R), when the current is maximum, the power is also maximum. Therefore, it is true that the power must be maximum at resonance.
12.
The power response of a series resonant circuit has a bell-shaped curve called the selectivity curve.
Correct Answer
A. True
Explanation
The power response of a series resonant circuit is determined by its selectivity, which refers to its ability to respond to a specific frequency while rejecting others. The selectivity curve of a series resonant circuit is bell-shaped, indicating that it has a peak response at the resonant frequency and gradually decreases as the frequency moves away from the resonant frequency. Therefore, the statement that the power response of a series resonant circuit has a bell-shaped curve called the selectivity curve is true.
13.
If the bandwidth of a circuit is kept very narrow , the circuit is said to have a Low selectivity
Correct Answer
B. False
Explanation
If the bandwidth of a circuit is kept very narrow, the circuit is said to have a high selectivity. This is because selectivity refers to the ability of a circuit to filter out unwanted signals and only allow a specific range of frequencies to pass through. When the bandwidth is narrow, the circuit becomes more selective and can effectively filter out unwanted frequencies. Therefore, the correct answer is False.
14.
The Bandwidth of the resonant circuit (BW) is The difference between the frequencies at which the circuit delivers half of the maximum power.
Correct Answer
A. True
Explanation
The bandwidth of a resonant circuit refers to the range of frequencies over which the circuit can effectively deliver power. It is defined as the difference between the frequencies at which the circuit delivers half of the maximum power. This means that within the bandwidth, the circuit is able to efficiently transfer energy. Therefore, the statement is true.
15.
The resonant frequency is the geometric mean of the half-power frequencies. The resonant frequency is the geometric sum of the half-power frequencies.
Correct Answer
B. False
Explanation
The resonant frequency is not the geometric sum of the half-power frequencies. The correct statement is that the resonant frequency is the geometric mean of the half-power frequencies. This means that the resonant frequency is the square root of the product of the two half-power frequencies.
16.
The “sharpness” of the resonance in a resonant circuit is measured quantitatively by the quality factor Q.
Correct Answer
A. True
Explanation
The quality factor Q is indeed used to measure the sharpness of resonance in a resonant circuit. It is a dimensionless parameter that represents the efficiency of energy transfer in the circuit. A higher Q value indicates a sharper resonance, meaning that the circuit can store and release energy more effectively. Conversely, a lower Q value indicates a broader resonance, indicating a less efficient energy transfer. Therefore, the statement is true.
17.
The quality factor of resonance circuit doesn't depent on resistance
Correct Answer
B. False
Explanation
The quality factor of a resonance circuit does depend on resistance. The quality factor, also known as Q factor, is a measure of the efficiency of a resonant circuit. It is determined by the ratio of reactance to resistance. Higher resistance in the circuit results in a lower Q factor, indicating lower efficiency. Therefore, the given statement is false.
18.
In series resonance, The higher the value of Q , the more selective the circuit is but more
bandwidth.
Correct Answer
B. False
Explanation
In series resonance, the higher the value of Q, the more selective the circuit is but less bandwidth. This means that a higher value of Q indicates that the circuit has a narrower range of frequencies that it can effectively amplify or resonate with. Therefore, the statement "The higher the value of Q, the more selective the circuit is but more bandwidth" is incorrect.
19.
In series resonance, If the band of frequencies to be selected or rejected is narrow,
the quality factor of the resonant circuit must be high.
Correct Answer
A. True
Explanation
In series resonance, the quality factor of the resonant circuit must be high when the band of frequencies to be selected or rejected is narrow. This is because a high quality factor indicates a narrow bandwidth, meaning that the resonant circuit can effectively select or reject specific frequencies within a narrow range. Therefore, the statement is true.
20.
At parallel resonance, the admittance consists only conductance G = 1/2R.
Correct Answer
B. False
Explanation
At parallel resonance, the admittance consists of both conductance (G) and susceptance (B). The conductance represents the real part of the admittance and is equal to 1/2R, where R is the resistance. However, the susceptance represents the imaginary part of the admittance and is not zero at parallel resonance. Therefore, the statement that the admittance consists only of conductance G = 1/2R is false.
21.
At parallel resonance,The value of current will be minimum since the total admittance is maximun
Correct Answer
B. False
Explanation
At parallel resonance, the value of current will be maximum, not minimum. This is because at resonance, the total admittance is maximum, which means the impedance is minimum. According to Ohm's Law, current is inversely proportional to impedance. Therefore, when impedance is at its minimum, the current will be at its maximum.
22.
At parallel resonance,The Power factor is unity.
Correct Answer
A. True
Explanation
At parallel resonance, the power factor is unity. This means that the current and voltage are in phase, resulting in an efficient transfer of power. At resonance, the reactive power is minimized, and the circuit behaves as if it only has resistive elements. Therefore, the power factor is equal to 1, indicating a balanced and efficient power transfer.
23.
At parallel resonance, The currents through the inductor and
the capacitor have the same
magnitudes but are 90 out of phase.
Correct Answer
B. False
Explanation
At parallel resonance, the currents through the inductor and capacitor are not 90 degrees out of phase. In fact, at parallel resonance, the currents through the inductor and capacitor are in phase, meaning they have the same phase angle. This occurs because at resonance, the reactances of the inductor and capacitor cancel each other out, resulting in a purely resistive circuit. Therefore, the given statement is incorrect.
24.
The magnitude of current in the reactive elements at parallel resonance is Q times Lower than the applied source current.
Correct Answer
B. False
Explanation
At parallel resonance, the magnitude of current in the reactive elements is higher than the applied source current, not lower. This is because at resonance, the reactive elements cancel out the reactive components of the source current, leading to a higher magnitude of current flowing through the reactive elements. Therefore, the statement that the magnitude of current in the reactive elements at parallel resonance is Q times lower than the applied source current is false.
25.
In practical parallel resonance , if the internal resistance of the coil is negligable , so the resonance frequency of the circuit will be equal to the resonant frequency of ideal parallel resonance
Correct Answer
A. True
Explanation
In practical parallel resonance, if the internal resistance of the coil is negligible, it means that the coil does not contribute any significant resistance to the circuit. Therefore, the resonance frequency of the circuit will be equal to the resonant frequency of ideal parallel resonance, where there is no internal resistance. This is because the presence of internal resistance in the coil affects the behavior of the circuit and can shift the resonance frequency. However, if the internal resistance is negligible, it will not have a significant impact on the resonance frequency, making the statement true.
26.
Active Filters consists of only passive elements R, L, and C.
Correct Answer
B. False
Explanation
Active filters do not consist of only passive elements R, L, and C. Active filters also include active components such as operational amplifiers or transistors to amplify or process the input signal. These active components allow for greater control and flexibility in shaping the frequency response of the filter. Therefore, the correct answer is False.
27.
Passive Filters consists of only passive elements R, and C.
Correct Answer
B. False
Explanation
Passive filters do not consist of only passive elements R and C. They can also include inductors (L) as passive elements. Therefore, the given statement is false.
28.
Passive Filters is more prefereable than Active filters
Correct Answer
B. False
Explanation
Passive filters are not necessarily more preferable than active filters. The choice between passive and active filters depends on the specific application and requirements. Passive filters are simpler and cheaper, but they have limitations in terms of frequency response and cannot amplify signals. Active filters, on the other hand, can provide amplification and have a wider range of frequency response. Therefore, the statement that passive filters are more preferable than active filters is false.
29.
Band pass filters are also called band reject filters
Correct Answer
B. False
Explanation
Band pass filters and band reject filters are two different types of filters. A band pass filter allows a certain range of frequencies to pass through while attenuating frequencies outside that range. On the other hand, a band reject filter, also known as a notch filter, attenuates a specific range of frequencies while allowing all others to pass through. Therefore, band pass filters and band reject filters are not the same, making the statement false.
30.
Band stop filters used to pass a certain band of frequencies
Correct Answer
B. False
Explanation
The given statement is false. Band stop filters, also known as notch filters, are used to block or attenuate a certain band of frequencies while allowing all other frequencies to pass through. They are the opposite of band pass filters, which are used to pass a certain band of frequencies and attenuate all others.
31.
Typical characterstics of filter response curve is more sharp than ideal chatacerstics
Correct Answer
B. False
Explanation
The statement suggests that the typical characteristics of a filter response curve are more sharp than ideal characteristics. However, the correct answer is False. In reality, the typical characteristics of a filter response curve are less sharp than ideal characteristics. Ideal characteristics refer to an ideal filter that has a perfectly sharp cutoff and no passband ripple, whereas real-world filters have some imperfections that cause a gradual transition between the passband and stopband.
32.
The RLC parallel resonant circuit provides a
bandpass filter when the output is taken
off the resistor
Correct Answer
B. False
Explanation
The RLC parallel resonant circuit does not provide a bandpass filter when the output is taken off the resistor. In this circuit configuration, the output is typically taken across the capacitor or inductor, not the resistor. The RLC parallel resonant circuit acts as a bandstop filter, also known as a notch filter, which attenuates a specific frequency or range of frequencies while allowing others to pass through.
33.
The RLC parallel resonant circuit provides a
band-stop filter when the output is taken
off the LC
Correct Answer
B. False
Explanation
The RLC parallel resonant circuit does not provide a band-stop filter when the output is taken off the LC. Instead, it provides a band-pass filter. In a band-pass filter, frequencies within a certain range, called the passband, are allowed to pass through while frequencies outside of this range, called the stopband, are attenuated. Therefore, the given statement is false.
34.
A filter that prevents a band of frequencies
between two designated values is called high stop filter
Correct Answer
B. False
Explanation
A filter that prevents a band of frequencies between two designated values is actually called a band-stop filter, not a high stop filter. A band-stop filter allows frequencies outside of the designated range to pass through while attenuating or blocking frequencies within the range. A high stop filter, on the other hand, is a filter that attenuates or blocks frequencies above a certain cutoff frequency. Therefore, the correct answer is False.
35.
For high pass filter, At high frequency Vout = 0
Correct Answer
B. False
Explanation
The statement "At high frequency Vout = 0" is not true for a high pass filter. In a high pass filter, the output voltage increases as the frequency of the input signal increases. Therefore, at high frequencies, the output voltage will not be zero.
36.
For Low pass filter, At low frequency Vout = 0
Correct Answer
B. False
Explanation
The statement "At low frequency Vout = 0" is not true for a low pass filter. In a low pass filter, low frequencies are allowed to pass through while high frequencies are attenuated. Therefore, at low frequencies, the output voltage (Vout) will not be zero. Hence, the correct answer is False.
37.
Second Order Filters contain two reactive elements (L and C)
Correct Answer
A. True
Explanation
Second order filters contain two reactive elements, namely inductors (L) and capacitors (C). These reactive elements are used to create a circuit that can selectively pass or reject certain frequencies of an input signal. The combination of these reactive elements allows the filter to have a steeper roll-off and a higher degree of frequency selectivity compared to first order filters, which only contain one reactive element. Therefore, the statement that second order filters contain two reactive elements (L and C) is true.
38.
Active filters Can generate gains greater than one
Correct Answer
A. True
Explanation
Active filters can generate gains greater than one because they are designed to amplify signals. By using active components such as transistors or operational amplifiers, active filters can increase the amplitude of the input signal. This amplification can result in a gain greater than one, allowing the output signal to be larger than the input signal. Therefore, it is true that active filters can generate gains greater than one.
39.
Active filters can be used to perform the same operations of passive filters
Correct Answer
A. True
Explanation
Active filters are electronic circuits that use active components such as transistors or operational amplifiers to filter and shape electrical signals. Passive filters, on the other hand, use only passive components like resistors, capacitors, and inductors. While passive filters are simpler and cheaper, active filters offer several advantages such as higher gain, adjustable cutoff frequency, and better performance in terms of accuracy and stability. Therefore, active filters can indeed perform the same operations as passive filters, but with additional benefits.
40.
Passive filters can be designed to generate output voltage greater than input voltage
Correct Answer
B. False
Explanation
Passive filters are designed to attenuate or reduce certain frequencies in a signal, not to increase the voltage. Therefore, it is not possible for passive filters to generate an output voltage greater than the input voltage.
41.
Transformer is the direct application for mutual inductance phenomena
Correct Answer
A. True
Explanation
The statement is true because a transformer is a device that utilizes mutual inductance to transfer electrical energy between two or more circuits. Mutual inductance occurs when the magnetic field produced by one coil induces a voltage in another coil. In a transformer, two coils, known as the primary and secondary windings, are wound around a common iron core. When an alternating current passes through the primary winding, it creates a changing magnetic field, which in turn induces a voltage in the secondary winding. This voltage can be stepped up or down depending on the number of turns in each winding, allowing for efficient power transmission and voltage transformation.
42.
No protection needed when the inductance from one coil can interfere with the operation of another adjacent component by means of electromagnetic induction
Correct Answer
B. False
Explanation
When the inductance from one coil can interfere with the operation of another adjacent component by means of electromagnetic induction, protection is indeed needed. This is because electromagnetic induction can induce unwanted voltage or current in nearby components, leading to interference and potential damage. Therefore, the correct answer is False.
43.
When two coils are close to each other, the magnetic flux caused by current in one coil links with the other coil.
Correct Answer
A. True
Explanation
When two coils are close to each other, the magnetic field produced by the current flowing through one coil is able to pass through the second coil, causing a magnetic flux that links the two coils together. This phenomenon is known as mutual inductance and is the basis for the functioning of transformers and other electromagnetic devices. Therefore, the statement is true.
44.
For Sinusoidal source d/dt =1/ jw
Correct Answer
B. False
Explanation
The given statement is false. The derivative of a sinusoidal source with respect to time is not equal to 1/jw. The correct expression for the derivative of a sinusoidal source is jw, where j represents the imaginary unit and w represents the angular frequency. Therefore, the given statement is incorrect.
45.
M21 relates the induced voltage in coil 1 to the current in coil 2
Correct Answer
B. False
Explanation
The statement is false because M21 actually relates the induced voltage in coil 2 to the current in coil 1, not the other way around. M21 is a mutual inductance coefficient that represents the coupling between two coils in an electromagnetic system. It quantifies how the changing current in one coil induces a voltage in the other coil.
46.
Mutual coupling exists when The inductors or coils are in far proximity
Correct Answer
B. False
Explanation
The statement is false because mutual coupling exists when the inductors or coils are in close proximity, not far proximity. Mutual coupling refers to the transfer of energy between two or more inductors that are closely placed together, allowing them to influence each other's behavior. When inductors are far apart, the mutual coupling is negligible.
47.
Mutual coupling exists when the circuits are driven by time-constant sources
Correct Answer
B. False
Explanation
Mutual coupling exists when two or more circuits are physically close to each other and their magnetic or electric fields interact with each other. It is not dependent on whether the circuits are driven by time-constant sources or not. Therefore, the statement that mutual coupling exists when the circuits are driven by time-constant sources is false.
48.
Mutual inductance M may be Negative or positive
Correct Answer
B. False
Explanation
Mutual inductance, denoted by M, is a property of two adjacent coils or circuits that describes the ability of one coil to induce a voltage in the other coil. It is always positive because it represents the coupling between the coils, regardless of the direction of the induced voltage. Therefore, the statement that mutual inductance M may be negative is incorrect.
49.
The mutual voltage may be negative or positive
Correct Answer
A. True
Explanation
The statement is true because the mutual voltage between two components in a circuit can be either positive or negative. The sign of the mutual voltage depends on the relative orientation of the components and the direction of the current flow. If the current flows in the same direction through both components, the mutual voltage will be positive. If the current flows in opposite directions, the mutual voltage will be negative. Therefore, the mutual voltage can take on either positive or negative values.
50.
In dot convention, if currents enter dotted terminals of two coils , M will be positive
Correct Answer
A. True
Explanation
In dot convention, the direction of the current flow is represented by a dot on one end of the coil. If the currents enter the dotted terminals of two coils, it means that the currents are flowing in the same direction. In this case, the mutual inductance (M) between the two coils will be positive.