WorksheetsM3_Mar 2012
Total questions: 30
Worksheet time: 15mins
The part of the transformer that is connected to the load is called the
primary winding.
secondary winding.
capacitor winding.
transistor winding.
In a transformer, the winding that produces the induced voltage is called
mutual winding.
primary winding.
induced winding.
secondary winding.
A step-down transformer with a turn ratio of 12:5 has 1080 turns on its primary winding. The secondary winding has
90 turns.
220 turns.
450 turns.
600 turns.
What is the ratio of a transformer that has a secondary voltage of 120 V when connected to a 2400 V supply?
1:20.
20:1.
1:200.
200:1.
In an op-amp shunt regulated power supply, the active current regulating component and the load are connected
in series.
in parallel.
as a close-loop.
as a open-loop.
The comparator circuit of a series voltage regulator compares the sense circuit voltage with the reference voltage and produces a voltage to
reduce the base current of the control element.
bias the control element into conducting a current.
compensate and maintain a constant output voltage.
ensure that the control element conducts current continuously.
One characteristics of all switch mode power supply is that they should not run without a
capacitor.
inductor.
load.
transformer.
The DC output voltage of a circuit drop from 100 V with no load to 95 V at full load. What is the load regulation percentage?
3.1%.
5.3%.
7.1%.
9.4%.
Refer to Figure 124. The current flowing through the zener diode is
2.5 mA.
3.6 mA.
9.2 mA.
12.4 mA.
Refer to Figure 122. The current flowing through the 20 V Zener diode is
2 mA.
4 mA.
6 mA.
8 mA.
How many classes of amplifier operation are there?
2.
3.
4.
5.
For a power transistor to operate at its maximum power rating, the transistor need to be mounted on a
heat sink.
plaster base.
wooden board.
glass mounting.
Quiescent operating point for Class A amplifier is
at the top of the load line.
at the centre of the load line.
at the bottom of the load line.
in between the cut-off and the bottom of the load line.
Refer to Figure 120. The capacitor, C1 is called
filter capacitor.
grounding capacitor.
coupling capacitor.
decoupling capacitor.
Refer to Figure 125. Calculate the voltage gain of the amplifier if the input peak-to-peak voltage is 2 V.
4.
8.
16.
32.
Which of the following coupling technique should be used when low frequency signals are Involved?
RC coupling.
Direct coupling.
lnductance coupling.
Transformer coupling.
Refer to Figure 126. Calculate the base current, IB .
9.3 µA.
93 µA.
100 µA.
200 µA.
One of the characteristics of the op-amp is that it has a very
high input current.
low input impedance.
high output impedance.
high open loop voltage gain.
Refer to Figure 128. The op-amp is connected as a/an
integrator.
differentiator.
inverting amplifier.
non-inverting amplifier.
Slew rate can be stated as:
A.
B.
C.
D.
The output of an op-amp rises by 1.4 V in 2 µs. What is the slew rate of the op-amp?
0.7 V/µs.
1 V/µs.
1.4 V/µs.
2.8 V/µs.
Which one of the following op-amp circuits has input voltage applied simultaneously to the inverting and non-inverting inputs of an op-amp?
amplifier.
Voltage follower.
Inverting amplifier.
Difference amplifier.
Non-inverting amplifier.
Refer to Figure 129. Calculate the voltage gain of the op-amp circuit shown.
0. 25.
4.
5.
100.
Refer to Figure 127. The voltage gain of the op-amp circuit = 20. Calculate the value of resistor, Rf.
38 kΩ.
40 kΩ.
42 kΩ.
44 kΩ.
The output frequency of a voltage-controlled oscillator is controlled by the input
dc voltage.
sine wave voltage.
square wave voltage.
triangle wave voltage.
Crystals are commonly used in oscillator circuits because higher
voltage gain can be generated.
feedback signals can be obtained.
frequency stability can be achieved.
operating temperature can be tolerated.
The input voltage to the voltage controlled oscillator is a
dc voltage.
ac voltage.
rms voltage.
peak-peak voltage.
Which one of the following filters is designed to reject a range of frequencies between the upper and lower cutoff frequencies?
Low-pass filter.
High-pass filter.
Band-stop filter.
Band-pass filter.
Refer to Figure 121. Assume that the op-amp is powered by ±20 V and can swing about ±18 V at its output. Determine the upper threshold point (UTP), given that UTP=Vmax(R1+R2R1)
- 3.88 V.
- 2.88 V.
+ 2.88 V.
+ 3.88 V.
Refer to Figure 123. Calculate the free-running frequency, fo , given that fo =R1 C 12(V+V +−Vc)
25.39 kHz.
30.39 kHz.
35.39 kHz.
40.39 kHz.
