physics prelim i 27 12 12

7/30/2019 Physics Prelim I 27 12 12

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H.S.C

Batch :

Date : 27/12/2012

SHRI CHANDRA TUTORIALSSCIENCE DEPARTMENT

PRILIMINARY EXAMINATION

PHYSICS

MARKS : 70

TIME : 3.00 HRS

Note : 1) All questions are compulsory.

2) Neat diagrams must be drawn whenever necessary.3) Figures to the right indicate full marks.

4) Use of only logarithms table is allowed.

5) All symbols have their usual meanings unless otherwise stated.

6) Answer to every question must be written on a new page.

7) Write answers of both sections in same answer book.

SECTION - I

Q.1) Select and write most appropriate answer from the given alternative for each

sub question : (7)1) The moment of inertia in rotational motion is analogous to. In translational

Motion.

a) Mass of body b) density of body c) angular velocity d) angular acceleration2) Youngs modulus for perfectly inelastic body is .

a) 0.5 b) 0 c) d) 13) the substance through which heat radiation can be transmitted are .

substance

a) athermanous b) diathermanous c) monatomic d) intermolecular force4) the ration of maximum acceleration at extreme position to maximum velocity at

mean position of a particle in SHM is .

a) amplitude b) angular velocity c) square angular velocity d) displacement5) S.I unit of Stefans constant is

a) b) c) d)6) When earth stops spinning about its axis then acceleration due to gravity remains

same at the .

a) poles b) equator c) center d) latitude 457) A person standing on railways platform. An engine blowing a whistle of 570 Hz

approaches him with a velocity of 36 . The frequency of note heard is .(Given : Speed of sound in air =340 )a) 580Hz b) 577.2 Hz c) 587.2 Hz d) 570 Hz

Q.2) Attempt any six from the following : (12)

1) Find the acceleration due to gravity at a depth of 2000 km from the earths surface

assuming that earth has uniform density [R=6400 km.]

2) Define period and frequency of a particle performing uniform circular motion.

State their S.I. units.


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3) A mass of 4 kg performs linear SHM. The restoring acting on it when it is at 20 cm

from the mean position is 5N. What is the value of periodic time of motion?

4) A steel blade floats on the surface of pure water. When detergent is added, it

sinks. Why?

5) What is the ration of angular speed of a minute hand and hour hand of a watch ?

6) Explain Maxwell distribution of molecular speed with graph.

7) The total energy of the surface of a liquid drop is 2 times the surface tension ofthe liquid. What is the diameter of the drop?

8) Derive an expression for moment of intertia of a solid about its tangent.

Q.3) Attempt any THREE from the following : (9)

1) What will be the duration of the day if the earth suddenly shriks to of itsoriginal volume, mass being unchanged?

2) Claculate the average molecular kinetic energy i) per kmole ii) per kilomole

iii) Per molecule of oxygen at 27

(R = 8320 K and Avogadros number =

3) Derive an expression for binding energy of a body at rest on the surface of the

earth.

4) Explain stress versus strain graph with the help of neat labeled diagram.

Q.4) A) i) From differential equation of linear S.H.M. obtain expression for acceleration,

Velocity and displacement of a particle performing S.H.M. (4)

ii) A transversal wave of amplitude 0.01 m and frequency 500Hz is travelling

along a stretched string with a speed of 200 . Find the displacement of aparticle at a distance of 0.7m from the origin after 0.01 second (3)

OR

B) i) Describe the sonometer experiment to verify different laws of vibrating string.

(5)

ii) A stretched sonometer wire is in unison with a tuning fork. When the lengh of

the wire is increased by 5%, the number of beats per second is 10. Find

frequency of the tuning fork. (2)

SECTION - II

Q.5) Select and write most appropriate answer from the given alternative for each

sub question : (7)

1) According to Newtons corpuscular theory, light is propagated in the form of ..

a) photons b) corpuscles c) waves d) electrons2) Kirchhoffs second law is based on the law of conservation of

a) charge b) energy c) momentum d) current3) The de-Broglies wavelength of an electron of energy 6000 eV is

a) 4 b) 20 c) 8 d) 16 4) Gausss law help in .

a) Situations where Coulombs law fails.


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b) Determination of electric field due to symmetric charge distribution.c) Determination of electric force between point charges.d) Determination of electric potential due to symmetric charges distribution.

5) In Photoelectric emission, if the maximum kinetic energy of the electron emitted

by photosensitive material is 6 eV, then stopping potential will be

a) 6 mV b) 6 V c) 0.6 mV d) 0.6 V6) The process in which some characteristic of high frequency square wave is

charged in accordance with the instantaneous value of modulation signal is

a) digital modulation b) analog modulation

c) amplitude modulation d) pulse modulation

7) Meter bridge is modification of .

a) galvanometer b) Wheat stones network c) potentiometer d) voltmeter

Q.6) Attempt any six from the following : (12)

1) Explain : is analogous to .2) In Fraunhofer diffraction due to a narrow slit, a screen is placed 2m away from

the lens to obtain the pattern. If the slit width is 0.2mm and first minimum lie 5

mm on either side of the central maximum, find the wavelength of light.

3) Draw a neat circuit diagram for a transistor as a CE amplifier and explain it.

4) A conductor of length 10 cm is moved parallel to itself with a speed of 10 atright angle to magnetic induction . Find the e.m.f. Induced in it

5) A planar loop of irregular shape encloses an area of 7.5 and carries acurrent of 6 A. the direction of magnitude dipole moment vector associated with

the current loop?

6) What is nuclear fusion?

7) Distinguish between P-types and N-types semiconductors.

Q.7) Attempt any THREE from the following : (9)

1) Sate and prove Gausss theorem in electrostatics.

2) The width of a plane incident wavelength is found to be doubled in a denser

medium. If it makes an angle of 70 with the surface, calculate refractive index forthe medium

3) Deduce Einsteins equation for a photoelectric effect and hence explain two

characteristics of photoelectric effect.

4) A galvanometer is shunted by()

its resistance. Find the fraction of the total

current passing through the galvanometer.

Q.8) A) i) Obtain an expression for power consumed in LCR series circuit. Hence

obtain an expression for power factor of the circuit. (4)

ii) A potentiometer wire has a length of 4m and a resistance of 10 . The wireis connected to a battery of emf 4V and internal resistance 2 . Find the


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potential difference per cm of the wire. What length of wire will balance a

cell of emf 1.5V? (3)

OR

B) i) Describe with neat diagram, the Fraunhofer diffraction pattern due to single

slit. (4)

ii) Find the velocity of electron in the ground state of hydrogen atom. Hence

find the velocity when the electron is in the fourth orbit. (3)

physics prelim i 27 12 12

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