Answer.2. Complete performance characteristics of the machine
Explanation:
An equivalent circuit of an electric machine helps us to determine the complete performance of the machine e.g efficiency, losses etc.
Ques 74. Which theorem is applicable for all types of networks whether it is linear, unilateral bilateral, quadrilateral, active, passive, linear, non-linear?
Thevenin
Norton
Maximum power transfer theorem
Tellegen
Answer.4. Tellegen
Explanation:
Tellegen’s theorem is one of the most powerful theorems in network theory. The physical interpretation of Te|legen‘s theorem is the conservation of power. As per the theorem, the sum of powers delivered to or absorbed by all branches of a given lumped network is equal to 0 i.e. the power delivered by the active elements of a network is completely absorbed by the passive elements at each instant of time.
Tellegen’s theorem depends on KCL and KVL but not on the type of the elements. Tellegen theorem can be applied to any network linear or non-linear, active or passive, time-variant or time-invariant.
Ques 75. The circuit shown in the figure given below represent a feedback amplifier. For this circuit, the current and voltage gains would respectively be
Answer.3. C
Explanation:
Ques 76. Unit of magnetic flux is
Tesla
Weber
A/T
None of these
Answer.2. Weber
Explanation:
The SI unit of magnetic flux is the weber (Wb) (in derived units: volt-seconds), and the CGS unit is the Maxwell.
Ques 77. The 6V Zener diode shown in the figure has zero Zener resistance and a knee current of 5 mA. The minimum value of R so that the voltage across it does not fall below 6V is
1.2 Ω
80 Ω
50 Ω
None of the above
Answer.2. 80 Ω
Explanation:
As R decreases current through it will increase.
Current supplied by 10V source is
I=(10-6)/50
I=80mA
I = Iz + IL
Iz is constant because input current is constant
If Iz is taking maximum current then the load will take minimum current
I = Izmax + ILmin
If Iz is taking minimum current then IL will take the max current when the load current is maximum then the minimum value of resistance R will be
I = Izmin + ILmax
80 = 5 + ILmax
The maximum current through R is 80-5=75mA = 75/1000 A
RLmin = Vz/ ILmax
= (6 x 1000)/75
=80Ω
Hence the minimum value of R so that the voltage across it does not fall below 6V is 80 ohms
Ques 78. In case of a short circuit _______ current will flow in the circuit.
Zero
Very Low
Normal
High
Answer.4. High
Explanation:
A short circuit occurs when the positive and negative terminals of a battery or any electrical appliances are connected with a low-resistance conductor, like a wire. With a low resistance in the connection, a high current will flow, causing the delivery of a large amount of energy in a short period of time.
Ques 79. A transistor has a current gain of 0.99 in the CB mode. Its current gain in the CC mode is
100
99
1.01
0.99
Answer.1. 100
Explanation:
In CB mode current gain is
Ic/IE = α
In CC mode current gain is
β =IC/IB
and β = α (1 – α)
= 0.99(1 – 0.99) = 99
Hence current gain = 1 + β = 1 + 99 = 100
Ques 80. The quantity of a charge that will be transferred by a current flow of 10 A over 1 hour period is?
