Transcript Slide 1

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 yaxis 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 A
d. 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.)
Read the following passage and answer the following
question:
•
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.
A
C
A
v
(8 ohm, 100 cm)
J
P
Q
20 V
2 ohm
Light
Wavelength
in
Angstrom
1
2
3
4
5
6
Violet
Blue
Green
Yellow
Orange
Red
40004500
45005000
50005500
55006000
60006500
65007000
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
(C)8.85 * 109
(B) 11.0625 * 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
(C) Red
(B) Violet
(D) Orange
4. Which of the color may not give photoelectric effect from this cathode
(A)
Green
(C) Red
(B) Violet
(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
0.1 m
1A
+
8N
1A
10N
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
Y
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
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
disceB/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
- - - - - - - - - -- - - - -- - - - - - - - - - h- - - - - - - - - - - - - - - - - - - - -B - - - - - - - - - - - - - - - - - L/3
- - - - - - L- air
- - - - - - - - --- -- - - - -- - - - - - - - - - - - - - -T - - - - - - - - - - - - - -- --2r-- - --- - - - - - - -
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