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Unique Science Academy

65-L, Gulberg III, Lahore.

Test physic part II Total time 3 hrs Total marks :

17+44+24=85

Name:

Encircle the most suitable answer 1*10=10.

i. Coulombs force in a medium strength r is

(a) vacr F (b)r

vacF

(c) medF (d) all

ii. The number of electrons removed from a body in order to produce +ve charge of

8x10-19c on it

(a) 9 (b) 7 (c) 5 (d) 3

iii. You are given three bulbs of 25, 40, 60 operating at same potential watt which of them has lowest

resistance

(a) 25 watt (b) 40 watt (c) 60 watt (d) None

iv. The maximum current that can allow to pass through a 100 watt lamp when 250 volts is

(a) 0.25A (b) 0.40A (c) 2.5A (d) 1 Amp

v. The value of 0 0 is equal to

(a) c

1

(b) c (c) 2

1

c (d) None

vi. An alpha moves in circular path of radius 0.45m in 1.2 Wbm-2. The speed of particle in ms-1 is

(a) 2.7x107 ms-1 (b) 2.7x103ms-1 (c) 2.7x106ms-1 (d) 2.7x104 ms-1

vii. Impedance for A.C circuit in

(a)rms

rms

I

V(b) 22 2 cfR + (c)

2

2 2

+L

R

(d) All

viii. The SI unit of stress is same as that of

(a) Momentum (b) Pressure (c) Force (d) Length

ix. Yttrium barium oxide can become superconductor at

(a) 1.18K (b) 3.72K (c) 125K (d) 16k

x. A two input NAND gate with inputs A and B has an output zero if

(a) A is 0 (b) B is 0 (c) Both A and B are zero (d) Both A and B are 1

xi. For pair production the energy of photon is

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(a) Equal to 1.02 Mev (b) Less than 1.02 Mev (c) greater than 1.02 Mev (d) May be

any value

xii. A high energy photon has wavelength

(a) Small (b) Large (c) Independent of wavelength (d) None of

these

xiii. Energy of K x rays is _____ than K x rays

(a) Less (b) Greater (c) equal (d) None of these

xiv. x rays cannot be

(a) Diffracted (b) reflected (c) scattered (d) charged

xv. Almost 99.9% of mass of an atom is concentrated in

(a) Electron (b) orbital part (c) neutron (d) nucleus

xvi. 1 = _____ kg

(a) 1.6606 x 10-27 (b) 1.6x10-19 (c) 9.1x10-31 (d) 6.02x1023

xvii. Shortest wavelength of ptund series is _____ mm

(a) 2258 (b) 2278 (c) 2288 (d) 2298

Answer the following short questions(any 14) 2*14=28.

i. If a charged particle moves in a straight line through some region, can you say that the

magnetic field in the region is zero?

ii. State Amperes law.

iii. Is it possible to change both the area of the loop and the magnetic field passing through the loop

and still not have an induced emf in the loop?

iv. Can an electric motor be used to drive an electric generator with the output from the

generator being used to operate the motor?

v. Define transformer, is energy conserve in case of transformer ?

vi. What condition under which electromagnetic waves produced?

vii. Show emf andt

have same unit

viii. Difference b/w resistance and resistivity.

ix. Difference b/w emf and p.d.

x. Difference b/w Ohmic and non-Ohmic.

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xi. Difference b/w charging and discharging of a capacitor.

xii. Do electrons tend to go to region of high potential or of low potential?

xiii. Show by electric polarization of dielectric capacitance of parallel plate capacitor increased.

xiv. What are the difficulties in testing whether the filament of a lighted bulb obeys Ohms law?

xv What is Wheatstone bridge? How can it be used to determine an unknown resistance?

ix. Describe a circuit which will give a continuously varying potential.

xvi Define potentiometer.

xvii. Define electrical power and showr

EP

4

2

max=

xviii. Why there is not charge on a n type or a p type substance?

xix. What is the effect of temperature on conductivity of semi conductors?

xx. Define paramagnetic and diamagnetic materials?

xxi. What is Remanance or Retantivity?

xxii. Sketch symbol of XNOR gate. Write its truth table.

xxiii. As solid is heated and begins to glow why does it first appear red?xxiv. When does light behave as a wave? When does it behave like particle?

xxv. What is Stefan Boltzman law?

xxvi. Define modulus of elasticity? Discuss its types?

xxvii. Define critical temperature and Curie temperature?

xxviii. Draw circuit for Full wave rectification?

Xxix Define spectroscopy. Differentiate b/w line and continuous spectrum.

xxx. Why we observe so many series in hydrogen emission spectra while it contain only one

electron?

xxxi. Find mass defect of4He nucleus.

xxxii. Write down fusion reaction in sun.

xxxiii. Define dose and equivalent dose and give their units.

long question 8*3=24

Q1 (a) What is rheostat? Discuss its working .

(c) A platinum wire has resistance of 10 at 0oC and 20 at 273oC. Find

value of temp co- efficient of resistance of platinum.

Q2 (a) Write a note on series R L circuit.

(b) When current through coil changes from mA to 200 mA in 0.005 s, an induced

emf of 40 mV is produced in the coil

(i) What is the self inductance of the coil?

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(ii) Find the increase in the energy stored in the coil

Q3 (a) What is photoelectric effect? Explain it and also discuss the results of

experiment.

(b) A 50 Kev photon is Compton scattered by a quasi free electron if

scattered photon comes off at 450 what is its wavelength.

Q4 (a) Write down Bohr postulates. By using this model calculate the radius and

energy.

(c) The wavelength of K x ray from copper is 1.377x10-10 m. What is the

energy difference b/w two levels from which this transition.

Q5 (a) derive a relation for strain energy in deformed materials.

(b) a 1.25cm diameter cylinder is subjected to load of 2500 kg . calculate the

stress on the bar in mega Pascal

1.