2nd Book Complete Improve
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Transcript of 2nd Book Complete Improve
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7/30/2019 2nd Book Complete Improve
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Ahmad Masood Physics (Improve) Complete book (2nd
year)
Q.1 Choose the Correct Answer
i. The number of electric field lines passing through a unit area held perpendicular to field linesrepresents (a) Electric potential (b) Electric intensity (c) Electric flux (d) none of these
ii. SI unit of electric flux is (a) Nm2C-1 (b) NmC-1 (c) Nm2C (d) Nm-2C-1iii. A wire of uniform area of cross section A and length L is cu t into two equal parts. The resistivity
of each part is (a) Doubled (b) Half (c) Remain the same (d) none of these
iv. Substances like germanium, silicon have (a) positive temperature coefficient (b) Negativetemperature coefficient (c) both a & b (d) none of these
v. Inside current carrying solenoid, the direction of magnetic field (a) is perpendicular to the axis ofsolenoid (b) at 60
owith axis (c) is along the axis (d) none of these
vi. If a charged particle moves in straight line through some region of space, then (a) no magnetic fieldin that region (b) magnetic field is parallel or anti parallel to motion of particle (c) magnetic field is
perpendicular to motion of particle (d) both a & b
vii. The induced current in a loop can be increased by (a) using a strong magnetic field (b) moving theloop faster (c) replacing loop by a coil of many turns (d) all of these
viii. The amplitude modulated transmission frequencies range from (a) 540 Hz to 1600 Hz (b) 540 kHz to1600 kHz (c) 540 MHZ to 1600 MHz (d) 88 MHz to 108 MHz
ix. Which one of the following is polymeric solid (a) Iron (b) Nylon (c) sodium chloride (d) Zirconiax. Given that IC = 100mA and IB is 40 A, then current gain of transistor is (a) 4 x 10-3 (b) 250 (c)
0.004 (d) 250 amp
xi. The output of two input OR gate is zero only when its (a) both inputs are zero (b) either input is zero(c) both inputs are one (d) either input is zeroxii. As temperature of platinum wire is increases the radiation becomes richer in (a) Shorter wavelength
(b) longer wavelength (c) much longer wavelength (d) none of these
xiii. Which phenomena confirm particle nature of light? (a) interference (b) diffraction (c) photoelectriceffect (d) polarization
xiv. The region in which lymen series lies is (a) infrared (b) ultraviolet (c) visible (d) none of thesexv. LASER beam is (a) Intense (b) Monochromatic (c) unidirectional (d) all of these
xvi. The unit of decay constant is (a) Second (b) (second)-1 (c) m-1 (d) mKxvii. The nergy released [er unit mass is greater in (a) fission reaction (b) fusion reaction (c) chemical
reaction (d) both a & b
Q.2 Give the short Answers. Attempt any 10.
1) Define electric intensity and give its SI unit.2) What is meant by electric polarization?3) Do electrons tend to go to region of high potential or of low potential?4) Why does resistance of conductor rise with temperature?5) What should be the orientation of a current carrying coil in a magnetic field so that torque acting on it
is (a) maximum (b) minimum6) State faraday law of electromagnetic induction and give its mathematical expression.7) How does doubling the frequency affect the reactance of (a) an inductor (b) a capacitor?8) What is meant by para and diamagnetic substances?9) Why is charge carriers not present in depletion region?10) What is net charge on n-type or p-type region?11) Can pair production take place in vacuum?12) Give two uses of LASER.13) What factors make a fusion reaction difficult to achieve?Attempt any 2
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Q.No 3. (a) Describe mass spectrograph. How nuclear masses are determined with it and isotopes are
detected?
(c) the half life of is 9.70 hours. Find its decay constant.
Q.4 (a) how e/m of an electron is calculated?
(b) how fast must a proton move in a magnetic field of 2.50 x 10-3
T such that the magnetic force is equal
to its weight. The mass of proton is 1.67 x 10-27
kg and its charge is q = 1.6 x 10-19
C.
Q.5 (a) explain the action of a transistor as an amplifier. Derive formula for its voltage gain.
(b) the current flowing into the base of a transistor is 100 A. find its collector current IC, its emmiter
current IE and ratio
, if its current gain is 100.