Download sample paper - Satyam Tutorials

SAMPLE PAPER (PHYSICS)
1. Two coils are placed close to each other. Write to factors on which the mutual
inductance of the pair of coils depend
2. A magnetic needle free to rotate in a vertical plain, orients itself vertically at a certain
place on the earth. What are the values of (i) horizontal component of earths magnetic
field and (ii) angle of dip at this place ?
3. Give one examples each of a system that uses the
(i)
Sky wave
(ii) space wave
mode of propagation
4. How does focal length of a lens change when red light incident on it is replaced by
violet light ? give reason.
5. If the electric flux entering and leaving an enclosed surface respectively is φ1 and φ2.
What is the electric charge inside the surface ?
6. A uniform wire of resistance 24Ω is cut into three equal lengths. One of these is formed
into a circle and connected between the other two. What is the resistance between the
opposite ends a and b ?
a
b
7. What would be the value of modulation index if the minimum amplitude AM wave is
zero volt.
8. A conductor of length l is connected to a dc source of potential V. if the length of the
conductor is tripled by gradually stretching it keeping V constant, how will drift speed of
electrons be affected ?
9. In a Youngs double slit experiment the intensity at a point where the path difference is
λ ∕ 6 is I. if I0 denotes the maximum intensity. Find the ratio of I and I0
10. Three point charges, which initially are infinitely apart, are placed at the corners of an
equilateral triangle with sides d. two of the point charges are identical and have charge
q. if zero net work is required to place the three charges at the corners of the triangle,
what must the value of the third charge be ?
OR
Deduce the expression for the potential energy of a system of two point charges q 1 and
q2 brought from infinitely to the points r1 and r2 respectively in the presence of external
electric field E.
11. When monochromatic light from a bulb falls on a photosensitive surface, the number of
photoelectrons emitted per second is n and their maximum kinetic energy is Kmax . if the
distance of the lamp from the surface is halved, then how do the number of
photoelectrons and Kmax be change?
12. The resistance of a wire is 5Ω at 50oC and 6Ω at 100oC. what would be the resistance of
the wire at 0o.
13. Using Gauss's law derive an expression for the electric filed intensity at any point
outside a uniformly charged thin spherical of a radius R and charge density σ cm-2. Draw
the field lines when the charge density of the sphere is (i) positive (ii) negative
14. An athlete peddles a stationary tricycle whose pedals are attached to a coil having 100
turns each of area 0.1 m2. The coil lying in the X – Y plane is rotated in this plane at the
rate of 50 rpm about the Y-axis in a region where, a uniform magnetic field. B = (0.01) k
tesla is present. Find the (i) maximum e.m.f. (ii) the average e.m.f. generate in the coil
over the complete revolution .
15. Draw a graph between frequency of incident radiation and maximum kinetic energy of
the electrons emitted from the surface of a photosensitive material. State clearly how
this graph can be used to determine (i) plank's constant and (ii) work function of the
material.
16. How does a light emitting diode (LED) work? Give two advantages of LED's over the
conventional incandescent lamps.
17. In the circuit shown in Fig. , find (a) the current in the 3.00-Ω resistor; (b) the unknown
emfs ε1 and ε2; (c) the resistance R. note that three currents are given.
2.00 A
R
ε1
ε2
+
4.00Ω
3.00 A
+
3.00 Ω
6.00 Ω
5.00 A
18. Using Bohr's postulates for hydrogen atom, show that the total energy (E) of the electron in the
stationary states can be expressed as the sum of kinetic energy (K) and potential energy (U),
where K = -2U. Hence, deduce the expression for the total energy in the nth energy level of
hydrogen atom
19. Three identical Polaroid sheets P1, P2 and P3 are oriented so that the (pass) axis of P2 and P3 are
inclined at an angle of 60o and 900 respectively with respect to the (pass) axis of P1. A
monochromatic source S, of intensity I0 is kept in front of the Polaroid sheet P1. Find the
intensity of this light as observed by observers O1, O2 and O3, positioned as shown
.
S.
O1
P1
O2
P2
O3
P3
20. Using ampere circuital law . Derive magnetic field at any point due to a long straight wire
carrying current. A horizontal overhead power line carries a current of 90A in east to west
direction. What is the magnitude and direction of the magnetic field due to the current 1.5 m
below the line?
21. Figure shows a real inverted image I of an object O is formed by a certain lens (not shown), the
object and image separation is d = 40cm measured along the central axis of the lens. The image
is just half the size of the object
(a) what kind of lens must be used to produce this image
(b) how far from the object must the lens be placed
(c) what is the focal length of the
lens ? complete the given diagram by showing lens and focus.
0
Lens here
d
i
22. (a) Using Bohr's second postulate of quantization of orbital angular momentum show
that the circumference of the electronic in the nth orbital state in hydrogen atom is n
times the de Broglie wavelength associated with it.
(b) The electron in hydrogen atom is initially in the third excited state. What is the
maximum number of spectral lines which can be emitted when it finally moves to the
ground state?
OR
Draw a plot of potential energy of a pair of nucleons as a function of their separations.
Mark the regions where the nuclear force is (i) attractive and (ii) repulsive. Write any
two characteristic features of nuclear forces.
23. Draw a plot of amplitude versus ω for an amplitude modulated wave. A message signal of
frequency 10 KHZ and peak voltage of 10 volts is used to modulate a carrier of frequency 1 MHz
and peak voltage of 20 volts. Determine:
(a) Modulation index (b) the side bands produced
24. A capacitor having a capacitance of 100 μF is charged to a potential difference of 50V. (a) what
is the magnitude of the charge on each plate? (b) the charging battery is disconnected and a
dielectric of dielectric constant 2.5 is inserted between the plates. (c) what charge would have
produced this potential difference in absence of the dielectric slab.
25. An electromagnetic wave of frequency ѵ = 3 MHz passes from vacuum in to a dielectric medium
with permittivity ϵr = 4. What happen to its frequency and wavelength.
Name the electromagnetic wave and order of its wavelength which is used in
(i)
Medicine to destroy cancer cells.
(ii)
Cellular phones and wireless networks.
26. Harsh was performing an experiment to carry out a project for that he required an ammeter of
range 0 – 7.5 A. It was not available in the laboratory and in the market. So he decided to
convert a galvanometer into an ammeter of given range. Full scale deflection current of
galvanometer is 1mA and it has 100Ω resistance.
(a) What values do you think are there in Harsh ?
(b) How could he do that ? explain by showing calculations.
(c) What is principle of galvanometer.
27. Derive an expression of motional electromotive force. A horizontal straight wire 10m long
extending from east to west is falling with a speed of 5ms-1 at right angle to the horizontal
component of the earths magnetic field, 3 x 10-5 Tesla.
(a) What is the instantenous value of emf induced in the wire?
(b) What is the direction of emf ?
(c) Which end of the wire is at the higher electrical potential ?
OR
A device consists basically of two coils in close proximity but not in electrical contact. It is
used to transform the voltage levels in an ac circuits.
(a) Such a device will work only with alternating current, however and not with direct
current. Explain.
(b) This device reduces the energy losses in the transmission lines. how?
(c) This device is connected to a 240V ac line to supply 12V to a portable electronic device.
The load resistance in the secondary is 5Ω
(i)
What should the ratio of primary to secondary turns of the device?
(ii)
What average power delivered to the load?
28. With the help of a block diagram explain principle of a transistor amplifier with positive
feedback working as an oscillator. Draw the circuit diagram of a tuned collector oscillator and
explain its working.
OR
Why is the base region of a transistor kept thin and lightly doped?
Draw the circuit diagram of the set-up used to study the characteristics of a npn transistor in its
common emitter configuration. Sketch the typical (i) input characteristics and (ii) output
characteristics for this transistor configuration .
How can the output characteristics be used to calculate the current gain of the transistor ?
29. (i) A thin lens , having two surfaces of radii of curvature r1 and r2 made from a material of
refractive index μ2 is kept in a medium of refractive index μ1. Derive the Lens Maker formula for
this set-up.
(iii)
A fish looking up through the water sees the outside world, contained in a circular
horizon. If the refractive index of water is 4 ∕ 3 and the fish is 12cm below the water
surface, find the radius of this circle.
OR
(a) Obtain the conditions for the bright and dark fringes in diffraction pattern due to a single
narrow slit illuminated by a monochromatic source.
Explain clearly why the secondary maxima go on becoming weaker with increasing n.
(b) When the width of the slit is made double, how would this affect the size and intensity of
the central diffraction band ? justify.