Physics

Which quantity in rotational motion is analogous to force in linear motion?

(A) Torque      (B) Moment of inertia     (C) Angular velocity        (D) Angular momentum

2. A particle undergoes SHM having time period T. What is the time taken by it to move from mean position to half of amplitude?

 (A)\( \frac{T}{2} \)

(B) \( \frac{T}{3} \)

(C) \( \frac{T}{6} \)

(D) \( \frac{T}{12} \)

Two capillary tubes A and B of radii 2mm and 4 mm are dipped in the same liquid. What is the ratio of heights through which liquid rises in the tubes A and B?

 (A) 1:2

(B) 2:1

(C) 1:4

 (D) 4:1

 An ideal liquid is taken through series of changes represented in diagram. The workdone by the gas at the end of cycle is  is a

(A) \( P_1V_1 \)

 (B) \( 5P_1V_1 \)

(C) \( 10P_1V_1 \)

(D) Zero

.A Carnot engine is working between 300K and 600K has output 200J. What is the energy supplied to the engine?

 (A) 400J       (B) 800J      (C) 1200J        (D) 1600J

The frequency of tuning fork is 384Hz and velocity of sound in air is 352m/s. How far the sound has transversed while fork complete 36 vibrations?

(A) 33m      (B) 36m       (C) 352m          (D) 72m

A ray of light strikes a glass plate at an angle of incidence\( 60^\circ \). If the reflected and refracted rays are perpendicular to each other in interface, what is the refractive index of glass?

 (A) \( \frac{1}{\sqrt{3}} \)

(B)\( \frac{\sqrt{3}}{2} \)

 (C) \( \frac{2}{\sqrt{3}} \)

(D) \( \sqrt{3} \)

Which of the following is the phenomenon of production of emf by maintaining a difference of temperature between two junctions of dissimilar metals?

 (A) Joule's effect      (B) Seebeck effect     (C) Peltier effect        (D) Thomson's effect

What happens to the susceptibility of ferromagnetic substance if temperature is decreased?

(A) Increases     (B) Decreases      (C) Remains same    (D) May increase or decrease

What is the induced emf in a coil if the flux associated with it changes at the rate of 1 Weber per minute?

 (a) 1 Volt       (b) \( \frac{1}{60} \)Volt     (c) 60 Volt        (d) Zero

Which of the earth quake waves is first recorded on the seismograph?

 (a) P-waves          (b) Rayleigh Waves      (c) S-Waves      (d) Love Waves

 a) Define angular momentum. Write its SI unit. 

b) The speed of a motor engine decreases from 900 rev/min. to 600rev/min. in 10 seconds.

Calculate: 3

i) The angular acceleration

ii) Number of revolutions made by the motor during this interval

iii) How many additional seconds are required for motor to come to rest in the same rate

             OR

a) For a simple pendulum, show that the acceleration is directly proportional to the displacement of bob from its mean position. 

b) A bob of mass 8kg performs SHM of amplitude 30cm. The restoring force is 60N. Calculate: 

i) Time period ii) The maximum acceleration iii) Kinetic energy when displacement is 12 cm.

In an experiment, a spherical ball of radius 'r' and density '\( ' \rho ' \) falls freely through the glycerin of density '\( \sigma \), as shown in figure.

a) Write the components of forces acting on the body by drawing free body diagram.                       

b) Sketch a graph by showing the nature of variation of velocity of ball with time. 

 c) If this drop soon attains constant downward velocity then find its expression. 

  Figure : 

 What is meant by entropy? Write the first law of thermodynamics in terms of entropy. 

 Can a room be cooled by leaving the door of an electric refrigerator open? Justify.  

c) A quantity of monoatomic gas at 30°C is compressed suddenly to \( (\frac{8}{27})^{th} \)parts of its initial volume. Find the change in temperature assuming \( \gamma (= \frac{C_p}{C_v}) \) to be \( \frac{5}{3} \) 

a) In Youngs double slits experiment, what changes will you observe in fringe width for the following operations:

 i) When experiment is shifted from air to inside water 

ii) When slits width is increased? 

 b) i) What is diffraction of light? 

 ii) Calculate the width of central diffraction peak on a screen 4m behind a 0.01m slit illuminated by 600nm light source. 

     OR

a) How can a spherical wave front be changed into plane wavefront? Draw a diagram to justify your answer.  

b) Apply Huygen's principle to verify the law of reflection of light. 

a) State and explain Bohr's postulates of an atomic model. 

b) i) Calculate the de-Broglie wavelength of a neutron having kinetic energy 150eV. 

 ii) A proton and an electron have same K.E. which one has greater de-Broglie wavelength?

[Given : Mass of neutron \( = 1.675 \times 10^{-27} \) kg, Planck's constant \( = 6.62 \times 10^{-34} \)JS]

a) During forward biasing of p-n junction diode, the width of depletion layer decreases. Justify. 

 b) Write the truth table for the combination of gates given in the figure below. 

c) Identify, which gate is obtained from the above combination of gates? 

a) Define self inductance of a coil.

b) A current from A to B is increasing in magnitude. What is the direction of induced current, if any, in the loop as shown in figure? Justify. 

c) Calculate the self inductance of a coil of 100 turns if a current of 2A gives rise to magnetic flux of \( 5 \times 10^{-3} \) Weber through the coil. 

a) Using Kirchhoff's laws of electrical circuit; derive an expression for balanced condition of Wheatstone bridge. 

 b) Conclude with the reason, where the balance point will be shifted, towards A or B when, 

 i) Resistance R is increased, keeping all other parameters constant .

ii) Resistance S is decreased , Keeping R is Constant .

a) Define an organ pipe. 

b) What is the ratio of length of two pipes, an open organ pipe A and a closed organ pipe B both vibrating in third overtones are in resonance? Justify. 

 c) In the given figure below, figure (i) represents a situation that both source of sound (S) and Listener (L) are at rest position 'S' and 'L' respectively. Figure (ii) represents relative motion between moving source and stationary listener. 

i) Does the pitch of sound changes to the listener in second case? Justify 

ii) Develop an expression to support your answer in (i).

d) Write any two properties of medium which is necessary for the propagation of sound. 

a) A graph between stopping potential (\( V_o \)) with the frequency (f) of incident radiation is shown in figure below. Answer the following questions.

i) Write the Einstein photoelectric equation in terms of stopping potential. 

ii) How will you determine Planck's constant from the graph? 

iii) What happens to stopping potential if frequency of incident photon increases gradually? Justify. 

b) In an experiment, voltage across two parallel plates is 50V and distance between them is 3cm. The magnetic field applied to make the beam undeflected is\( 10^{-4} \) Tesla.

i) Why electron beam remains undeflected? 

ii) Calculate the velocity of electron passing through the fields? 

       OR

a) Define the term radioactivity. 

b) Two radioactive samples A and B have equal number of atoms initially. Their half lives are 3 hours and 9 hours respectively. Compare their rate of disintegration after 18 hours from start. 

c) Develop a relation between half life and decay constant of a radioactive sample. 

d) What percentage of atoms decayed after five half life periods? Justify your answer with calculation. 

    Graph : 

a) Two conductors X and Y carrying currents \( I_1 \) and \( I_2 \) are placed in air at a distance r apart as shown in figure.

i) Find the magnitude of force between them. 

 ii) What is the nature of force in this case? 

iii) Define one ampere current on the basis of the force between parallel current carrying conductors. 

b) Figure shows a rectangular metal frame ABCD placed in a uniform magnetic field of flux density\( 4.5 \times 10^{-3} \) T.

OR  

a) Define impedance of LCR circuit. 

b) A series LCR circuit is given in figure.

i) Calculate the impedance of the circuit if \( L=60\text{mH} \), \( C=0.50\mu\text{F} \) and \( R=300\Omega \) 

ii) How does resonance occur in above LCR circuit? Write the required expression

c) A device is connected across an ac source of voltage \( V=V_0 \sin \omega t \) and the current through X is given by\( I=I_0 \sin (\omega t + \frac{\pi}{2}) \)

i) Identify, which device is X? Also, write the expression for its reactance. 

ii) Draw graphs showing the variation of voltage and current with time over one cycle of an alternating current for X .