PHYSICS PAPER 12TH CLASS 2019 OBJECTIVE SARGODHA BOARD GROUP 2
PHYSICS
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Sargodha
Board 2019
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GROUP II
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Maximum Marks: 17
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OBJECTIVE
TYPE
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Time Allowed: 20 Minute
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Q.1. (A) Choose the correct option from the columns A, B, C and D
and fill up the bubbles: 17
1.
If the
distance between two charges is halved, the force between them becomes
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Double
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Half
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Four times
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One time
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2.
When some
dielectric inserted between the plates of a capacitor then capacitance
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Increased
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Decreased
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Zero
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Infinity
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3.
Kitchhoff’s
First Rule is a manifestation of law of conservation of
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Mass
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Energy
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Charge
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Momentum
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4.
Work done on
a charge particle moving in a uniform magnetic field of
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Maximum
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Zero
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Minimum
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Negative
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5.
Output wave
form of weep or time base generator is
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Saw tooth wave
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Digital wave
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Sinusoidal wave
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Square wave
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6.
Energy stored
in inductor is
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½ LI
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½ L2I
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½ L2I2
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½ LI2
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7.
Which one is
not present in A.C generator
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Armature
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Magnet
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Slip rings
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Commutator
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8.
At high
frequency the value of reactance of capacitor is
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Small
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Zero
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Large
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Infinite
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9.
In three
phase A.C. generator the phase different between each pair of coil is
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45o
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60o
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90o
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120o
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10. The substance in which atoms cooperate with each other in
such a way, so as to exhibit a strong
magnetic field is called
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Paramagnetic
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Diamagnetic
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Ferro magnetic
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Non magnetic
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11. A sensor of light is
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Transistor
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LED
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Diode
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Light dependent resistance
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12. Find the gain of inverting amplifier of external resistance R1=10KΩ
and R2= 100KΩ
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-5
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-10
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-2
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50
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13. The value of Stefen’s constant is
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2.9 x 10-3mK
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1.097 x 107 m-1
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6.63 x 10-34 J.s
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5.67 x 10-8Wm-2 K-4
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14. The factor 4/moc has the dimension of
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Length
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Time
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Mass
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Energy
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15. Which series lies in the ultra violet region
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Balmer series
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Bracket series
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Pfundseried
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Lyman series
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16. Absorbed does D is defined as
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Transistor
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LED
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Diode
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Light dependent resistance
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17. A proton consists of quarks which are
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2 up and 1 down
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1 up and 2 down
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All up
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All down
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PHYSICS PAPER 12TH CLASS SUBJECTIVE 2019 SARGODHA BOARD GROUP 2
PHYSICS
|
Sargodha
Board 2019
|
Group II
|
Maximum
Marks: 88
|
SUBJECTIVE
TYPE
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Time Allowed:
2:30 hours
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SUBJECTIVE
TYPE
(PART-1)
Q2. Write short answers to any EIGHT (8)
questions: (2x8=16)
(i)
Describe the force or
forces on a positive point charge when placed between parallel plates with
opposite and equal charges.
(ii)
Is E necessarily zero
inside a charged rubber balloon if balloon is spherical? Assume that charge is
distributed uniformly over the surface.
(iii)
What is time constant of
a capacitor?
(iv)
Prove that I volt/meter=
I newton/coulomb
(v)
Suppose that a charge q
is moving in a uniform magnetic field with a velocity. Why there is no work
done by the magnetic force that acts on the charge q?
(vi)
Why the resistance of an
ammeter should be very low?
(vii)
Write use of CRO.
(viii)
Define magnetic flux and
one tesla.
(ix)
State Faraday’s Law and
writ its mathematical form.
(x)
How power loss due to
eddy currents in transformer can be reduced?
(xi)
Does the induced emf
always act to decrease the magnetic flux through a circuit?
(xii)
How would you position a
flat loop of writ in a changing magnetic field so that there is no emf induced
in the loop.
Q3. Write short answers to any EIGHT (8)
questions: (2x8=16)
(i)
Do bends in a writ affect
its electrical resistance?
(ii)
What are the difficulties
in testing whether the filament of a lighted bulb obeys Ohms law?
(iii)
Under what conditions
e.m.f of a cell and terminal potential difference become equal.
(iv)
What is choke? Write its
main use.
(v)
Define ultimate tensile
strength and fracture stress.
(vi)
How will you obtain
N-type and P-type material from silicon?
(vii)
How many times per second
will an incandescent lamp reach maximum brilliance when connected to a 50 Hz
source?
(viii)
A sinusoidal current has
rms value of 10 A. What is the maximum or peak value?
(ix)
Distinguish between
crystalline and polymeric solids.
(x)
The anode of a diode is
0.2 C positive with respect to cathode, is it forward biased?
(xi)
Why a photodiode is
operated in a reverse biased state?
(xii)
Name any two basic
characteristics of op-Amplifier. Also give their approximate values.
Q4. Write short answers to any NINE (9)
questions: (2x9=18)
(i)
Does brightness of beam
of light primarily depends upon the frequency of photons or on the number of
photons?
(ii)
Why can red light be used
in a photographic dark room when developing films but not blue or white light?
(iii)
We do not notice the
dc-Broglie wavelength for a pitched cricket ball. Explain why?
(iv)
Why Laser action cannot occur without
population inversion between atomic levels?
(v)
What is meant by line
spectrum? Explain how line spectrum can be used for the identification of
elements?
(vi)
If a nucleus has a
half-life of 1 year, does this mean that it will completely decay after 2
years? Explain.
(vii)
What is radioactive
tracer? Describe one application in medicine and agriculture.
(viii)
Write a short note on
Geiger Muller Counter.
(ix)
Define Mass defect and
Binding energy.
(SECTION-1I)
Note: Attempt any THREE questions.
Q5. (a) Derive and expression for Energy stored
by the capacitor.
(b) 1.0 c 107 electrons pass
through a conductor in 1.0us. Find the current in ampere flowing through the
conductor. Electronic charge is 1.6 x 5 10-19 C.
Q6. (a) Define motional emf. Derive a relation
for motional emf.
(b) What current should pass through a
solenoid that is 0.5m long with 10,000 turns of copper wire so that it will
have a magnetic field of 0.4 T.?
Q7. (a) What is transistor? Describe the use of
transistor as an amplifier and derive its voltage gain.
(b) An alternating source of emf 12 V and
frequency 50 Hz is applied to a capacitor of capacitance 3uF in series with a
resistor of resistance 1KΩ. Calculate the phase angle.
Q8. (a) What is energy band theory? How it can
be used to explain the features of electrical conductors, insulators and
semiconductors.
(b) What is mass of a 70 kg man in a space
rocket travelling at 0.8 c from us as measured from earth?
Q9. (a) Define solid state detector. Give its
principle, construction and its working.
(b) Find the speed of electron in the first
Bohr orbit.
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