QUESTION

1.A body is kept such that its centre of mass lies on X-axis. Its moment inertia about an axis passing through (x,0)& parallel to y-axis is given by I=X2 -2X+2(0<X<4). Find the x-coordinate of CM.

A.2 B.1 C.5 D.3

2.A solid of radius R of bulk modulus K is surrounded by a liquid in a cylindrical container. A mass less piston of area A floats on the surface of the liquid. When a mass m is placed on the piston to compress liquid, the fractional change in radius of sphere is

a. mg/AK b.mg/3AK c. mg/A d.mg/3AR

1. A- A very thin air film between two glass plates appear dark by reflected light.

B- Total phase difference of is created only by reflection & not by path difference.

a. Only A is true b. only B is true c. B is true & is reason of Ad. Both true but B is not reason of A

1. Given two steel balls of same size. One ball is at rest on the horizontal plane, while other is suspended from a fine chord made from a good insulator. The centre of gravity of the two balls are at the same horizontal level at the beginning of the experiment. The same quantity of heat is supplied to both balls. The change of temperature of both balls is same. (All kinds of heat losses are negligible) (see fig.)

• The voltage across the electrode is measured with an ideal voltmeter, which can be varied by moving jockey (J) on the potentiometer wire. Ammeter is ideal. CSA of plates in the vacuum tube is 50 cm(2) ; Distance between them is 0.5 mm. Photocurrent in the circuit is very small so that we can treat potentiometer circuit as independent circuit.

Read the following passage and answer the following question:

v

A C

(8 ohm, 100 cm)

2 ohm20 V

P QJ

A

Light 1Violet

2Blue

3Green

4Yellow

5Orange

6Red

Wavelength

in

Angstrom

4000-4500

4500-5000

5000-5500

5500-6000

6000-6500

6500-7000

1.The no. of electrons appeared on the surface of the cathode plate, when the jockey is connected at the end of the potentiometer wire. Assume that no radiation is falling on the plates.

(A) 8.85 * 106 (B) 11.0625 * 109

(C)8.85 * 109 (D) Zero

2. When radiation falls on cathode plate a current of 2 (mu)A is recorded in the ammeter. Assuming that the vacuum tube setup follows Ohm’s Law, the equivalent resistance of vacuum tube operating in this case when jockey is at the end P.

(A) 8 * 108 (B) 16 * 106

(C) 8 * 106 (D) 10 * 106

3. It is found that ammeter current remains unchanged (2 (mu) A) even when the jockey is moved from the end ‘P’ to the middle point of the potentiometer wire. Assuming all the incident photons eject electron and the power of the light incident is 4 * 10(-6) W. Then the colour of incident light is

(A) Green (B) Violet

(C) Red (D) Orange

4. Which of the color may not give photoelectric effect from this cathode

(A) Green (B) Violet

(C) Red (D) Orange

• When other light falls on the anode plate the ammeter reading remains zero till, jockey is moved from the end P to the middle point of the wire PQ. Thereafter the deflection is recorded in the ammeter. The maximum kinetic energy of the emitted electron is

a. 16eV b.8eV c.4eV d.10eV

Q. In a cell unit positive charge experience a constant non electric force of 10N & a constant electric force of 8N in directions shown in figure. EMF=_ _

Ans. 1v

+10N8N

0.1 m

1A1A

Q. H-atom in a sample are excited to same energy level n=5 & it is found that photons of all possible wavelengths are released when the atoms return back to the ground state. The minimum no. of H-atoms in the sample is

a. 10 b. 6 c.4 d.5

Q.A wedge shaped vertical soap film (u=4/3) of length 2.75cm is illuminated normally by red light of wavelength 600nm(in vacuum). Six horizontal bright bands appear on the film due to reflected light. Angle of wedge (very small) is 4.5*10(-5)

Q.A tightly-wound long solenoid is kept with its axis parallel to a large metal sheet carrying a surface current. The surface current through a width dl of the sheet is Kdl & the number of turns per unit length of the solenoid is n. The magnetic field near the centre of solenoid is 0. If the solenoid is rotated by 180 about the line which is perpendicular to solenoid axis, the magnitude of the magnetic field near its centre is _ _ _ _ u0k

Q. A man can swim in still water with a speed of 3m/s.River flows to

the right with a speed of 1m/s

The man starts swimming from origin O at t=0. Assuming size of man to be negligible ,equation of locus of all the possible points where man can reach at t=1s is

(x-1)2+y2=9

X

Y

Q.A string of length l fixed at both ends vibrates in resonance with a tuning fork of frequency f at two successive values of tension T1 & T2 in the string. Specific mass of string is

Q.A conducting disc of radius R is placed in a uniform magnetic field B parallel to the axis of the disc. Angular speed with which the disc should be rotated about its axis such that no electric field develops in the disc-

eB/m

Q. A light cylindrical tube T of length l & radius r containing air is inverted in water (density d1). One end of the tube is open & other is closed. A block B of densityd2 (>d1) is kept on the tube as shown in the figure. The tube stays in equilibrium in the position shown. Find the volume of B. The density of the air is negligible

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

- - - - - - - - - - - - - - - - - - - - - - - - - - - -

- - - - - - - - - - - - - - - - - - - - - - - - -- - - - - - - -

- - -

air- - - - -- - - - - - - - - -

L/3L

B

h

2rT

Q. A hollow cylinder is closed at both ends of length L & mass m & is attached with a spring of force constant K. An equal mass with radius is kept inside the cylinder. Initially the string is stretched by a distance L. No friction & collisions are elastic. Initially mass is touching that side of cylinder which is connected with spring. Time period of the resultant motion is