PUNJAB Academy CHINIOT
Paper for Entry Test Preparation
Physics 2nd year Chapter No. 16
Total marks:- 160 Time
allowed 25 minutes
Note:- Fill
the appropriate answer of the following questions in the answer sheet. Double
filling and erasing is not allowed. Each question carries equal marks and for
each wrong answer minus one is awarded.
1) Alternating current is produced by a voltage
source which polarity:
a)
Remains the same b) Reverse
after period T c) Keeps on
reversing d) All of above
2) Now a days, most of the electrical energy is
produced by A. C generator using:
a)
Hydral water b)
Geothermal energy c) Solar
energy d) Biomass
3) The most common source of alternating voltage is:
a)
Motor b)
Transformer c) AC
generator d) Both
(a) and (c)
4) The waveform of alternating voltage is a:
a)
Square b)
Rectangular c)
Saw-tooth d)
Sinusoidal
5) The highest value reached by the voltage or
current:
a)
In quarter cycle is called instantaneous value b)
In half cycle is called peak to peak value
c)
In one cycle is called peak value d)
In half cycle is called instantaneous value
6) The sum of positive and negative peak values
(i.e. p-p value) is called:
a)
Instantaneous value b) Peak
value c) RMS
value d) Peak to
peak value
7) Peak value of alternating current is:
a)
One of its instantaneous values b)
Equal to its RMS values
c)
The same as its peak to peak value d)
Both (b) and (c)
8) Power delivered during a cycle:
a)
Is zero b)
Is not zero c)
Depends upon I d)
Depends upon I2rms
9) The magnitude of alternating voltage V:
a)
Always increases b)
Always decreases c) Remains
constant d) Non of all
10) If we connect an AC voltmeter to read AC
voltage, it would read its:
a)
RMS value b)
Instantaneous value c) Average
value d) Zero
11) A sinusoidally alternating voltage or current
can by graphically represented by a:
a)
Vector b)
Rotating vector c) Clockwise
rotating vector d) Anticlockwise
voltage vector
12) The basic circuit element in a DC circuit is:
a)
A capacitor b) A
resistor c) An
inductor d) Both
(a) and (c)
13) The current and voltage in an AC circuit can be
controlled:
a)
Only be a resistor b) Only
by a capacitor c) Only be an
inductor d) Both (a) and (c)
14) Instantaneous values of an alternating voltage
are sine function which vary with:
a)
Time b)
Speed c)
Acceleration d)
Current
15) When an alternating voltage is applied to a
capacitor, the charge q deposited on the
capacitor:
a)
Is in phase with applied voltage b)
Is out of phase
c)
Leads the voltage d)
Lags behind the voltage
16) When AC voltage source is connected to a
capacitor:
a)
V lags behinds I b) I
leads V c) V
leads I d)
Both (a) and (b)
17) Is case of capacitor, the unit of reactance is:
a)
Farad b)
Newton c)
Ohm d)
All of above
18) An inductor usually has:
a)
Small value of inductance (L) and negligible resistance R b) Large value of L and negligible R
c)
Small value of L and large value of R d)
Both L and R large
19) To maintain the current in a inductor, the
applied alternating voltage must be:
a)
Equal to back emf b)
Greater than back emf c) Smaller
than back emf d) Non of these
20) Inductive and capacitive reactance are expressed
respectively in the unit of:
a)
Ohm and Ohm b) Ohm and
Farad c c)
Henry and Farad d) Henry
and Ohm
21) The capacitive reactance is proportional:
a)
Directly to f b)
Inversely to f c)
Inversely to C d)
Both (a) and (c)
22) In case of AC opposition if offered by:
a)
Resistor b)
Inductor c)
Capacitor d)
All of above
23) Impedance is the combined effect of:
a)
Resistance and capacitance b) R and L c) L and C d) R and
reactance
24) Impedance is expressed in:
a)
Henry b)
Ohm c)
Farad d)
Tesla
25) Power dissipation is zero in a pure:
a)
Resistive circuit b)
Inductive circuit c)
Capacitive circuit d) Either (b) or (c)
26) When the frequency of AC source connected to
R-L-C series circuit is very small then:
a)
KL > XC b)
XL = XC c)
XC > XL d)
Non is true
27) A high frequency of the voltage applied to an
R-L-C series circuit, the circuit behaves like:
a)
R-C series circuit b) L-C series circuit c) R-L series circuit d) Any of these
28) At resonance condition in an R-L-C series
circuit, XL and XC are:
a)
Equal to each other b)
Opposite to each other c) Both (a)
and (b) d) Unequal
29) Power factor is defined by:
a)
Tan j b) Sin j c)
Cos j d) Cot j
30) Resonance frequency, the impedance of an R-L-C
series circuit is:
a)
Zero b)
Minimum c) R d) Both
(b) and (c)
31) In a three phase AC generator there are three coils
each connected to its own pair:
a)
Split rings b)
Commutators c) Both
(a) and (b) d) Splip
rings
32) Three phase AC generator with common junction of
the coil earthed, has only:
a)
Two terminals b) Three
terminals c) Four
terminals d) Five terminals
33) For detection of metals, we use:
a)
R-L circuit b)
R-C circuit c)
L-C circuit d)
Any of these
34) The electrical components which together can
produce oscillations of currents are:
a)
Coil and the resistor b)
Inductor and the coil c) Coil and
the capacitor d) Resistor
and the choke
35) Which of the following are not electromagnetic
waves:
a)
Radio waves b)
Sound waves c)
Infrared waves d) Alpha
particles
36) While tuning a radio station on a radio set, we
usually change:
a)
Value of L b) Value of C c) Voltage d) Current
37) For modulation purpose, high frequency radio
waves are called:
a)
Audio waves b)
Carrier waves c)
Longitudinal waves d) Signal
38) Modulation is achieved by changing the:
a)
Amplitude of the modulating signal b) Frequency of
carrier wave
c)
Amplitude of the carrier waves d)
Either (b) or (c)
39) The waves which do not travel in vacuum with
speed of light are the:
a)
Sound waves b)
X-rays c)
Gamma-rays d) Infra
red waves
40) The process of combining low frequency signal
with a high frequency radio waves is called:
a)
Amplification b)
Rectification c)
Modulation d)
Demodulation
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