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Wednesday, 26 February 2020

PHYSICS PAPER 12TH CLASS 2019 SARGODHA BOARD GROUP 2


PHYSICS PAPER 12TH CLASS 2019 OBJECTIVE SARGODHA BOARD GROUP 2

PHYSICS
Sargodha Board 2019
GROUP II
Maximum Marks: 17
OBJECTIVE TYPE
Time Allowed: 20 Minute
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
Double
Half
Four times
One time
      2.      When some dielectric inserted between the plates of a capacitor then capacitance
Increased
Decreased
Zero
Infinity
      3.      Kitchhoff’s First Rule is a manifestation of law of conservation of
Mass
Energy
Charge
Momentum
      4.      Work done on a charge particle moving in a uniform magnetic field of
Maximum
Zero
Minimum
Negative
      5.      Output wave form of weep or time base generator is
Saw tooth wave
Digital wave
Sinusoidal wave
Square wave
      6.      Energy stored in inductor is
½ LI
½ L2I
½ L2I2
½ LI2
      7.      Which one is not present in A.C generator
Armature
Magnet
Slip rings
Commutator
      8.      At high frequency the value of reactance of capacitor is
Small
Zero
Large
Infinite
      9.      In three phase A.C. generator the phase different between each pair of coil is
45o
60o
90o
120o
     10.  The substance in which atoms cooperate with each other in such  a way, so as to exhibit a strong magnetic field is called
Paramagnetic
Diamagnetic
Ferro magnetic
Non magnetic
     11.  A sensor of light is
Transistor
LED
Diode
Light dependent resistance
     12.  Find the gain of inverting amplifier of external resistance R1=10KΩ and R2= 100KΩ
-5
-10
-2
50
     13.  The value of Stefen’s constant is
2.9 x 10-3mK
1.097 x 107 m-1
6.63 x 10-34 J.s
5.67 x 10-8Wm-2 K-4
     14.  The factor 4/moc has the dimension of
Length
Time
Mass
Energy
     15.  Which series lies in the ultra violet region
Balmer series
Bracket series
Pfundseried
Lyman series
     16.  Absorbed does D is defined as
Transistor
LED
Diode
Light dependent resistance
     17.  A proton consists of quarks which are
2 up and 1 down
1 up and 2 down
All up
All down
PHYSICS PAPER 12TH CLASS OBJECTIVE 2019 SARGODHA BOARD GROUP 2

PHYSICS PAPER 12TH CLASS SUBJECTIVE 2019 SARGODHA BOARD GROUP 2
PHYSICS
Sargodha Board 2019
Group II
Maximum Marks: 88
SUBJECTIVE TYPE
Time Allowed: 2:30 hours

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.

PHYSICS PAPER 12TH CLASS 2019 SARGODHA BOARD GROUP 2
PHYSICS PAPER 12TH CLASS 2019 SARGODHA BOARD GROUP 2

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