1.A 8Ω resistance wire is bent at the middle by 1800 . Both the halves are twisted together. what is the new resistance?
2.State Brewster’s law.The value of Brewster angle for a transparent medium is different for light of different colours. Give reason.
3.Calculate the temperature at which the resistance of a conductor becomes 20% more than its resistance at 270 C. The value of the temperature coefficient of resistance of the conductor is 2 x 10-4 K
4.We do not choose to transmit an audio signal by just directly converting it to an e.m. wave of the same frequency. Give two reasons for the same.
5.In a potentiometer arrangement for determining the emf of a cell, the balance point of the cell in open circuit is 350 cm.When a resistance off 9 Ω is used in the external circuit of the cell, the balance point shifts to 300 cm.Determine the internal resistance of the cell.
6.Two cells of emf E1 and E2 have internal resistance r1 and r2 . Deduce an expression for equivalent emf of their parallel combination.
7.Explain any two applications of eddy current.
8.In double-slit experiment using light of wavelength 600 nm, the angular width of a fringe formed on adjacent screen is 0.1˚. What is the spacing between the two slits?
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9.Calculate the frequency of the photon which can excite an electron to -3.4 eV from -13.6 eV.
10.Draw a circuit diagram to show, how is a photo diode biased?
11.The work function of lithium is 2.3 eV. What does it mean? What is the relation between the work function ‘ωo’ and threshold wavelength ‘λo’ of a metal?
12.Draw a labelled ray diagram showing the formation of image of a distant object using an astronomical telescope in the near point adjustment.
13.Draw a circuit diagram to show how a photodiode is biased. Draw its characteristic curves for two different illumination intensities.
14.Electrons are emitted from the cathode of a photocell of negligible work function, when photons of wavelength λ are incident on it. Derive the expression for the de Broglie wavelength of the electrons emitted in terms of the wavelength of the incident light.
15.A mass of 4 kg is tied at the end of a string 1.2 m long, revolving in a horizontal circle. If the breaking tension in the string is 200 N, find the maximum number of revolutions per minute the mass can make.
16. (i) Write two characteristics of a material used for making permanent magnets.
(ii) Why is core of an electromagnet made of ferromagnetic materials?
17.Using Ampere's circuital law, derive an expression for the magnetic field along the axis of a toroidal solenoid.
18. Fig. shows a light bulb (B) and iron cored inductor connected to a DC battery through a switch (S).
(i) What will one observe when switch (S) is closed?
(ii) How will the glow of the bulb change when the battery is replaced by an ac source of rms voltage equal to the voltage of DC battery? Justify your answer in each case.
19.Two electric bulbs P and Q have their resistances in the ratio of 1:2.They are connected in series across a battery.Find the ratio of the power of dissipation in these bulbs.
20.(i) State the principle on which the working of an optical fiber is based.
(ii) What are the necessary conditions for this phenomenon to occur?
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21.Sketch a schematic diagram depicting electric and magnetic fields for an electromagnetic wave propagating along the Z-direction.
22.Draw V-I graph for ohmic and non-ohmic materials. Give one example for each.
23.How does the self-inductance of an air core coil change, when (i) the number of turns in the coils is decreased & (ii) an iron rod is introduced in the coil.
24.Derive the expression for the electric potential at any point along the axial line of an electric dipole?
25.The two graphs drawn below, show the variation of electrostatic potential (V) with 1/r (r being distance of the field point from the point charge) for two point charges q1 and q2 .
(i) What are the signs of the two charges?
(ii) Which of the two charges has a larger magnitude and why?
27. What do the terms ‘depletion region’ and ‘barrier potential’ mean for a p-n junction?
28.Light of wavelength 550 nm. is incident as parallel beam on a slit of width 0.1mm. Find the angular width and the linear width of the principal maxima in the resulting diffraction pattern on a screen kept at a distance of 1.1m from the slit. Which of these widths would not change if the screen were moved to a distance of 2.2m from the slit?
29.What is neutron multiplication factor? For what value of this, a nuclear reactor is said to be critical?
30.A parallel beam of light is incident normally on a plane surface absorbing 40% of the light and reflecting the rest. If the incident beam carries 10W of power, find the force exerted by it on the surface.
31.If the path difference produced due to interference of light coming out of two slits for yellow colour of light at a point on the screen be 3λ/2, what will be the colour of the fringe at that point? Give reasons.
32.Two coils P and S are arranged as shown in the figure. (i) What will be the direction of induced current in S when the switch is closed? (ii) What will be the direction of induced current in S when the switch is opened?
33.A convex lens is differentiated to n regions with different refractive indices. How many images will be formed by the lens?
34.Obtain an expression for the capacitance of a parallel plate capacitor.
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35.A wire placed along north south direction carries a current of 5 A from South to North. Find the magnetic field due to a 1 cm piece of wire at a point 200 cm North East from the piece.
36.An electron moving with Kinetic Energy 25 keV moves perpendicular to a uniform magnetic field of 0.2 mT. Calculate the time period of rotation of electron in the magnetic field.
37.A parallel beam of light of wavelength 600 nm is incident normally on a slit of width ‘a’. If the distance between the slits and the screen is 0.8 m and the distance of 2nd order maximum from the centre of the screen is 15 mm, calculate the width of the slit.
38.A Zener diode has a contact potential of .8Vin the absence of biasing .It undergoes breakdown for an electric field of 10V/m at the depletion region of p-n junction.If the width of the depletion region is 2.4µm?What should be the reverse biased potential for the Zener breakdown to occur?
39.An electron and a proton are moving in the same direction and possess same kinetic energy. Find the ratio of de-Broglie wavelengths associated with these particles.
40.Derive the Bohr’s quantisation condition for angular moment of the orbiting of electron in hydrogen atom, using de Broglie’s hypothesis.
41.Depict the behaviour of magnetic field lines near
(i) Diamagnetic
(ii) Paramagnetic substance. Justify, giving reasons.
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41.Depict the behaviour of magnetic field lines near
(i) Diamagnetic
(ii) Paramagnetic substance. Justify, giving reasons.
42.Two identical loops, one of copper and the other of aluminum, are rotated with the same angular speed in the same magnetic field. Compare (i) the induced emf and (ii) the current produced in the two coils. Justify your answer.
43.A 100 Ω resistor is connected to 220V, 50 cycles per seconds. What is (i) peak potential difference (ii) average potential difference and (iii) rms current?
44. Write the principle of (i) a meter bridge. (ii) a potentiometer.
45.A coil of mean area 500 cm2 having 1000 turns is held perpendicular to a uniform magnetic field of 0.4 G. The coil is turned through 180 o in 1/10 seconds. Calculate the average induced e.m.f.
46. 11kw of electric power can be transmitted to a distant station at (i) 220V and (ii) 22kV. Which of the two modes of transmission should be preferred and why?
47.Answer the following questions:
(a) How does the size and intensity of the central maxima changes when the width of the slit is double in a single slit diffraction experiment?
(b)In what way is diffraction from each slit related to the interference pattern in a double slit experiment?
(c)When a tiny circular obstacle is placed in the path of light from a distant source,a bright spot is seen at the centre of the shadow of the obstacle. Explain why?
48.The variation of potential difference "V" with length "l" in the case of two potentiometers "X" & "Y" is as shown in figure. Which one of these two will you prefer for comparing emf's of two cells and why?
49.A small illuminated bulb is at the bottom of a tank, containing a liquid of refractive index μ upto a height H. Find the expression for the diameter of an opaque disc, floating symmetrically on the liquid surface in order to cut-off the light from the bulb.
50.Show that the radius of nth orbit in hydrogen atom varies as n2, where n is the principal quantum number of the orbit.
51.Electromagnetic radiations with wavelength
(i) are used to kill germs in water purifiers.
(ii) are used in TV communication systems
(iii) play an important role in maintaining the earth’s warmth. Name the part of electromagnetic spectrum to which these radiations belong. Arrange these wavelengths in decreasing order of their magnitude.
52.We do not choose to transmit an audio signal by just directly converting it to an E.M wave of the same frequency. Give two reasons for the same.
53.The susceptibility of a magnetic material is -1.6 x 10-5 . Identify the type of the magnetic material and write its two properties.
54.A transmitting antenna at the top of tower has a height of 36m and the height of the receiving antenna is 49m. What is the maximum distance between them, for the satisfactory communication in the LOS mode? (Radius of the earth = 6400 km).
55.The magnifying power of an astronomical telescope in the normal adjustment position is 100. The distance between the objective and the eyepiece is 101 cm. Calculate the focal lengths of the objective and of the eye-piece.
56.Can peak voltage across an inductor be greater than the peak voltage supplied to an LCR?
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57.Find the equivalent capacitance between X and Y.
58.A coil of wire of certain radius has 600 turns and inductance of 108mH. What will be the inductance of another similar coil with 500 turns?
59.State Brewster’s law.The value of Brewster angle for a transparent medium is different for light of different colours. Give reason.
60.(i) Define refractive index of a medium.
(ii) In the following ray diagram, calculate the speed of light in the liquid of unknown refractive index.
61.A 10 V cell of negligible internal resistance is connected in parallel across a battery of emf 200V and internal resistance 38 Ω as shown in the figure.Find the value of current in the circuit.
62. Draw a graph to show the variation of resistance R of the metallic wire as a function of its diameter D keeping the other factor constant.
63.Electric charge is distributed uniformly on the surface of a spherical rubber balloon.Show how the value of electric intensity and potential vary
i] on the surface
ii] inside and outside
64.An electric dipole ±4µC is kept at coordinate points (1, 0, 4) are kept at (2,-1, 5), the electric field is given by = 20 NC-1 . Calculate the torque on the dipole.
65.Find the resistance between the points (i) A and B and (ii) A and C in the following network
66.If a constant current of 2.8A exists in a resistor, what is the rms value of current? Why?
67.Two nuclei P & Q have equal no: of atoms at t=0.Their half lives are 3 & 9 hours respectively. Compare the rates of disintegration after 18 hours from the start.
68.A charge q of mass m is moving with a velocity v, at right angles to the uniform magnetic field B. Deduce the expression for the radius of the circular path it describes.
69.A simple harmonic progressive wave of frequency 5 Hz is travelling along the positive X direction with a velocity of 40 m/s. Calculate the phase difference between two points separated by a distance of 0.8 m.
70.Distinguish between broadcast mode and point-to-point mode of communication and give on example for each.
71.Write two points of difference between n-type and p-type semiconductors.
72.A device X used in communication system can convert one form of energy into another.Name the device X. Explain the function of a repeater in a communication system.
73.Define the term ‘angle of dip’. What is the value of the angle of dip at the magnetic equator? What does it mean?
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74.A wire of length 0.04m carrying a current of 12 A is placed inside a solenoid, making an angle of with its axis. The field due to the solenoid is 0.25 T. Find the force on the wire.
75.An electric dipole is free to move in a uniform electric field. Explain its motion when it is placed
I] parallel to the field,
ii] perpendicular to the field
76.The potential across a generator is 125V when it is suppling10A. When it supplies 30A, the potential is 120V. What is the resistance of the armature and induced e.m.f?
77.-Explain the terms
(i) Attenuation and
(ii) Demodulation used in Communication System
78.Use the mirror equation to show that an object placed between f and 2f of a concave mirror forms and image beyond 2f.
79.Use de-Broglie’s hypothesis to write the relation for the nth radius of Bohr orbit in terms of Bohr’s quantization condition of orbital angular momentum.
80.An LCR series circuit is connected to an AC source. Which of its components dissipates power? L or C or R? Justify your answer.
81.Show that Bohr's second postulate 'the electron revolves around the nucleus only in certain fixed orbits without radiating energy can be explained on the basis of de Broglie hypothesis of wave nature of electron
82.Write the expression for the electric field, charge density for a uniformly charged thin spherical shell.
83.A solenoid is 1m long and 3 cm in mean diameter. It has 5 layers of windings of 800 turns each and carries a current of 5 A. Find Magnetic Field Induction at the center of the solenoid.
84.Two thin lenses when in contact produce a net power of +10D. If they are at 0.25m apart, the net power falls to +6 D. Find the focal lengths of the two lenses.
85.4 nuclei of an element fuse together to form a heavier nucleus .If the process is accompanied by release of energy, which of the two: the parent or the daughter nuclei would have higher binding energy per nucleon. Justify your answer.
86.Calculate the shortest wavelength of light emitted in the Paschen series of hydrogen spectrum. Which part of the electromagnetic spectrum, does it belong? (Given: Rydberg constant, R = 1.1x 107 m-1)
87. (a) Why are infrared waves often called heat waves? Explain
(b) What do you understand by the statement, “Electromagnetic waves transport momentum”?
88.A nucleus with mass number A = 240 and BE/A = 7.6 MeV breaks into two fragments each of A = 120 with BE/A = 8.5 MeV. Calculate the release energy.
89.Distinguish between polarized and unpolarized light.Does the intensity of polarized light emitted by a polaroid depend on its orientation? Explain briefly.
The vibrations in a beam of polarized light make an angle of 60o with the axis of the polaroid sheet.What percentage of light is transmitted through the sheet?
90.Define magnetic susceptibility of a material. Name two elements, one having positive susceptibility and the other having negative susceptibility. What does negative susceptibility signify?
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91.The voltage and current in a series AC circuit are given by V= V0 Cosωt & I= I0 Sinωt. What is the power dissipated in the circuit?
92.Calculate the force between two alpha particles kept at a distance of 0.02mm in air.
93. A uniformly charged rod with linear charge density λ of length L is inserted into a hollow cubical structure of side ’L’ with constant velocity and moves out from the opposite face. Draw the graph between flux and time.
94.Two identical coaxial coils carry equal currents. What will happen to the current in each loop if the loops approach each other?
95.Name the characteristics of e. m. waves that: (i) increases, & (ii) remains constant in e. m. spectrum as one moves from radio wave region towards ultraviolet region.
96.Distinguish between ‘Intrinsic’ and ‘extrinsic’ semiconductors.
97.A carrier wave of peak voltage 15V is used to transmit a message signal.Find the peak voltage of the modulating signal in order to have modulation index of 60%.
98.The wavelength λ of a photon and the de-Broglie wavelength of an electron have the same value.Show that energy of a photon is (2 λ mc/h) times the kinetic energy of electron, where m,c and h have their usual meaning.
98.The wavelength λ of a photon and the de-Broglie wavelength of an electron have the same value.Show that energy of a photon is (2 λ mc/h) times the kinetic energy of electron, where m,c and h have their usual meaning.