Physics Set A

8/12/2019 Physics Set A

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Prelim1 Etech-Academy

Time:3Hrs Date:23/12/2013

PHYSICS: SECTION I

Q. 1. Select and write the most appropriate answer rom the !i"en alternati"es or each s#$%estion: '()

i. The moment of inertia of a thin uniform rod of mass M and length L, about an axis passing through a point,midway between the centre and one end, perpendicular to its length is ______.

(A)!

ML" (#)$

ML" (%)&

ML" (')&

ML"

$ ! ! &

ii. n* droplets of e+ual sie of radius r coalesce to form a bigger drop of radius -. The energy liberatedis e+ual to _______. (T /urface tension of water)

& &

(A) 0-"T1 n 2&3 (#) 0r"T1 n 2&34 4

" "

(%) 0-"T1 n 2& 3 (') 0r"T1 n 2& 34 4

iii. The buc5ling of a beam is found to be more if _______.(A) the breadth of the beam is large.(#) the beam material has large 6alue of 7oung*s modulus.(%) the length of the beam is small.(') the depth of the beam is small.

i6. 8hen a trans6erse wa6e on a string is reflected from the free end, the phase change produced is_______.

(A) ero rad (#) 0rad (%)40

rad (') 0 rad"

6.The number of degrees of freedom for a rigid diatomic molecule is _______.(A) 4 (#) 9 (%) (') $

6i. Two particles perform linear simple harmonic motion along the same path of length "A and period T ashown in the graph below. The phase difference between them is _______.

'isplacem

ent

:

AA

";

< & T 4T T

A

"

(Time)

:

(A) ero rad (#) 0rad (%) 0rad (')40

rad

"


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6ii. The light from the /un is found to ha6e a maximum intensity near the wa6elength of $= nm. Assuming th

surface of the /un as a blac5 body, the temperature of the /un is _______.18ien*s constant b ".!>! ? &=24m@3

(A) 9!== @ (#) =9= @ (%) & @ (') 9== @

Q. *. +ttempt an, SI-: '1*)

i. /tate @epler*s law of orbit and law of e+ual areas.

ii. A car of mass. &9== @g rounds a cur6e of radius "9=m at >= @mhour. %alculate the centripetal force acting

on it.

iii. 'raw a neat labelled diagram for Berry*s perfectly blac5 body.

i6. A mass M attached to a spring oscillates with a period of " seconds. Cf the mass is increased by " @g, theperiod increases by & second. Bind the initial mass, assuming that Doo5e*s law is obeyed.

6.'ifferentiate between free and forced 6ibrations.

6i. The surface tension of water at =E% is $9.9 dynecm. Bind surface tension of water at "9E%. 1F for water

=.=="&E%3

6ii. 'eri6e the relation between surface tension and surface energy per unit area.

6iii. A wheel of moment of inertia & @gm"is rotating at a speed of = rads. 'ue to friction on the axis, the wheecomes to rest in &= minutes. %alculate the angular momentum of the wheel, two minutes before it comes torest.

Q. . +ttempt an, TH/EE: '0)

(i) A particle of mass m, Gust completes the 6ertical circular motion. 'eri6e the expression for the difference in

tensions at the highest and the lowest points.

(ii) The Harth is rotating with angular 6elocity I about its own axis. - is the radius of the Harth. Cf -I" =.=44!ms", calculate the weight of a body of mass &== gram at lattitude "9E. (g >.! ms")

(iii) 'eri6e an expression for 5inetic energy, when a rigid body is rolling on a horiontal surface without slipping

Dence find 5inetic energy for a solid sphere.

(i6) A steel wire of diameter & ? &=24m is stretched by a force of "= J. %alculate the strain energy per uni6olume. (7 steel " ? &=&&Jm")

Q. . 'efine an ideal simple pendulum. /how that, under certain conditions, simple pendulum performs linear

simple harmonic motion. '()A train blows a whistle of fre+uency = D in air. Bind the difference in apparent fre+uencies of the whistle for a

stationary obser6er, when the train mo6es towards and away from the obser6er with the speed of $" @mhour

1/peed of sound in air 4= ms.3

O/

8ith a neat labelled diagram, show that all harmonics are present in an air column contained in a pipe open at both

the ends. 'efine end correction.


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%alculate the 5inetic energy of &= gram of Argon molecules at &"$E%. 1Kni6ersal

gas constant - !4"= 5 mole @, Atomic weight of Argon =3

PHYSICS: SECTION II

Q.1. Select and write the most appropriate answer rom the !i"en alternati"es or each s#$%estion : '()

i. Cn the diffraction pattern due to a single slit of width d* with incident light of wa6elength *, at an anglof diffraction N*, the condition for first minimum is _______.

(A) sin N d (#) d cos N (%) d sin N (') cos N d

ii. @irchhoff*s Gunction law is e+ui6alent to _______.(A) conser6ation of energy(#) conser6ation of charge

(%) conser6ation of electric potential(') conser6ation of electric flux

iii. let p* and H* denote the linear momentum and energy of emitted photon respecti6ely. Cf the wa6elengtof incident radiation is increased _______.(A) both p and H increase(#) p increases and H decreases(%) p decreases and H increases(') both p and H decrease

i6. The nuclei ha6ing same number of protons but different number of neutrons are called_______.

(A) isobars (#) F O particles

(%) isotopes (') P O particles

6. Cn case of transistor oscillator, to obtain sustained oscillations, the product of 6oltage gain withoufeedbac5 and feedbac5 factor should be _______.(A) ero (#) less than &

(%) one (') infinity

6i. The process of regaining of information from carrier wa6e at the recei6er is called _____.(A) modulation (#) transmission

(%) propagation (') demodulation

6ii. -eactance of a coil is &9$ Q.


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iii. %).6. 'efine magnetiation. /tate its formula and /.C. unit.6i. Hlectrostatic energy of 4.9 ? &=2 is stored in a capacitor at $== . 8hat is the charge on the capacitorS

6ii. 8hat is space wa6e propagationS /tate its three components.

6iii. Bind the 6alue of energy of electron in e in the third #ohr orbit of hydrogen atom. (-ydberg*sconstant (-) &.=>$ ? &=$m2&,Ulanc5*s constant (h) .4 ? &=24 V s, elocityof light in air (c) 4 ? &=!ms.)

Q.. +ttempt an, TH/EE: '0)

i. 8ith the help of neat labelled circuit diagram explain the wor5ing of half wa6e rectifier usingsemiconductor diode. 'raw the input and output wa6eforms.

ii. A cell balances against a length of "== cm on a potentiometer wire, when it is shunted by a resistance o!Q. The balancing length reduces by = cm, when it is shunted by a resistance of Q. %alculate thebalancing length when the cell is in open circuit. Also calculate the internal resistance of the cell.

iii. /tate the law of radioacti6e decay. Dence deri6e the expression J Joe2twhere symbols ha6e theirusual meanings.

i6. The photoelectric wor5 function for a metal is ." e. Cf the stopping potential is 4, find the thresholdwa6elength and maximum 5inetic energy of emitted electrons.(elocity of light in air 4 ? &=!ms, Ulanc5*sconstant .4 ? &=24 V s, %harge onelectron &. ? &=2&>%)

Q.. /tate Baraday*s laws of electromagnetic induction and Len*s law. '()

Uro6e theoretically, the relation between e.m.f. induced and rate of change of magnetic flux in a coil mo6ing in auniform magnetic field.

A circular coil of "9= turns and diameter &! cm carries a current of &"A. 8hat is the magnitude of magneticmoment moment associated with the coilS

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Physics Set A