Recent questions tagged mock-test-series-2015

A) With the help of a labeled circuit diagram explain the rectification action of a full wave rectifier b)What are energy bands? How are these formed? Distinguish between a conductor, insulator, and a semiconductor on the basis of the energy band diagram.

asked Jan 30, 2015 by meena.p

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Sonia was watching a movie, in which he saw the automatic opening of a garage door. She was fascinated about this and asked her brother to explain about this. Even though her brother did not know much about this he decided to learn about this and explain it to Sonia. He came to know about the photoelectric effect in the automatic opening of the door. He explained about this in detail to Sonia. She thanked him for this. a) What are values of Sonia’s brother in enlightening her about the subject? b) How is photoelectric effect involved in the automatic opening of the garage door? c) Why alkali metals are most suitable for photoelectric emission?

asked Jan 30, 2015 by meena.p

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Sona was often surprised by the reproduction of sound in cinemas. She asked her uncle about this. Even though her uncle didn’t know much about this, he decided to give Sona a clear picture about the reproduction of sound in cinemas. He went to the operator of the projector of the cinema hall and learnt about this. Then he took Sona to the projector room and the operator explained about this very clearly. She thanked her uncle. A) What according to you are the values displayed by Sona’s uncle? B) What is the role of Photoelectric effect in the reproduction of sound in cinema film? C) State two different situation in which free electrons may be emitted from a surface.

asked Jan 30, 2015 by meena.p

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a) Why is Diamagnetism independent of temperature? b) State and prove tangent law in magnetism c) What happens if an iron bar is melted? Will it regain its magnetism?

asked Jan 30, 2015 by meena.p

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What are coherent sources of light? Deduce an expression for the intensity at any point on the screen in Young’s double slit experiment. What is a Polaroid? How is plane polarized light obtained with its help? How will you use it to distinguish between unpolarised light and plane polarized light.

asked Jan 30, 2015 by meena.p

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A) Calculate the equivalent resistance between the points M and N. B) Deduce Ohms’s law using the concept of drift velocity and relaxation time.

asked Jan 30, 2015 by meena.p

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A pure inductor is connected across an a.c. source. Show mathematically that the current in it lags behind the applied e.m.f by a phase angle of $\large\frac{\pi}{2}$ What is its inductive reactance? Draw a graph showing variation of inductive reactance with the frequency of the a.c. source.

asked Jan 30, 2015 by meena.p

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Explain the term FAX. Distinguish between FAX and E-Mail.

asked Jan 30, 2015 by meena.p

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The ground state energy of hydrogen atom is $-13.6\;eV$ 1.What are the potential and kinetic energy of an electron in the 3rd excited state? 2.If the electron jumps to the ground state from the third excited state, calculate the frequency of the photon emitted.

asked Jan 30, 2015 by meena.p

1 answer

a) Define ‘disintegration constant’ and ‘mean life’ of a radioactive substance. Give the unit for each. b)Obtain the amount of $^{60}Co_{27}$ necessary to provide a radioactive source of $8.0\;mCi$ strength. The half life of $^{60}Co_{27}$ is $5.3$ years.

asked Jan 30, 2015 by meena.p

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The potential difference across the collector of a transistor, used in common emitter mode is $1.5\;V,$ with the collector resistance of $3\;k \Omega.$ Find 1. The emitter and 2. The base current, if the d.c. gain of the transistor is $50$

asked Jan 30, 2015 by meena.p

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Draw a ray diagram of an astronomical telescope in the near point adjustment position, Write the expression for its magnifying power .

asked Jan 30, 2015 by meena.p

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Describe the principle construction and uses of a choke coil. A coil is represented as $z = (8+6j)\; ohm$. Calculate the inpedence of the coil.

asked Jan 30, 2015 by meena.p

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A storage battery of e.m.f of $12.0\; V$ and internal resistance $0.5 \omega$ is to be charged by a $120\;V$ d.c. supply of negligible resistance. What resistance is required in the circuit for the charging current to be $3\; A?$ What is the terminal voltage of the battery during the charging?

asked Jan 30, 2015 by meena.p

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A) Two point charges of values $q$ and $2q$ are kept at a distance d apart from each other in air. A third charge $Q$ has to be kept along the same line in such a way that the net force acting on q and $2q$ is zero. Calculate the position of charge $Q$ in terms of q and d. b)A capacitor of capacitance C is charged fully by connecting it to a battery of e.m.f ‘e’. It is then disconnected from the battery. If the separation from the plates of the capacitor is $b$ now doubled, what will be a) charge stored in the capacitor? b) potential difference across it c) field strength between the plates d) energy stored by the capacitor

asked Jan 30, 2015 by meena.p

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a) A bubble inside a glass slab appears to be at a depth of $3\;cm$ from one face and $2\;cm$ from opposite face. If $\mu= 1.5,$ what is the actual thickness of the slab? b) An astronomical telescope consists of two thin lenses set $36\;cm$ apart and has a magnifying power of $8$. Calculate the focal lengths of the lenses.

asked Jan 30, 2015 by meena.p

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(A) Draw a labeled diagram to show the formation of the image of a distant object through a reflecting telescope (B) A converging lens has a focal length of $20\; cm$ in air. It is made of refractive index $1.6$. If it is immersed in a liquid of refractive index $1.3,$ what will be its new focal length?

asked Jan 30, 2015 by meena.p

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A metal has a threshold wavelength of $6000 ^{\circ} A$. Calculate its 1) threshold frequency and 2) work function of the metal in eV.

asked Jan 29, 2015 by meena.p

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Prove that an ideal capacitor , in an a.c. circuit does not dissipate power.

asked Jan 29, 2015 by meena.p

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Define $\alpha$ and $\beta$ of a transistor. How are they related?

asked Jan 29, 2015 by meena.p

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A)Name any two modes of modulation used for pulsed waves. B) What is the order of energy gap in an insulator?

asked Jan 29, 2015 by meena.p

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The sequence of the stepwise decay of radio active nucleus is If the nucleon number and atomic number for $D_2$ are respectively 176 and 71, what are the corresponding values for D and $D_4$ nuclei? Justify your answer.

asked Jan 29, 2015 by meena.p

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Name two factors on which the resisitivity of a given material depends. A carbon resistor has a value of 62 KΩ with a tolerance of 5%. Give the color code of this resistor.

asked Jan 29, 2015 by meena.p

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A straight wire of length of $1.5\;m$ and mass $200\;g$ carries a current of $2A$. It is suspended in mid-air by a uniform horizontal magnetic field B. What is the magnitude of the magnetic field?

asked Jan 29, 2015 by meena.p

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State Lenz’s law. On which law of conservation is it based?

asked Jan 29, 2015 by meena.p

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What is the de-Broglie wavelength of an electron accelerated from rest through a potential difference of V volts?

asked Jan 29, 2015 by meena.p

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How does the electric field of an electric dipole vary with distance?

asked Jan 29, 2015 by meena.p

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What is the ratio of infra red rays to ultra violet rays in vaccum?

asked Jan 29, 2015 by meena.p

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Why are microwaves used in Radar?

asked Jan 29, 2015 by meena.p

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Why does the acceleration of a magnet falling through a long solenoid decrease?

asked Jan 29, 2015 by meena.p

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Draw a circuit diagram and explain the operations of a transistor as a switch .

asked Jan 28, 2015 by meena.p

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(a)Draw a circuit diagram of an n-p-n transmitter with its emitter base function forward biased and base collector junction reverse biased. Describe briefly its properties (b) Explain how a transistor in active state exhibits a low resistance at its emitter base junction and high resistance at its base collector junction .

asked Jan 28, 2015 by meena.p

1 answer

a) Explain the formation of depletion layer and barrier potential in a P-n junction . (b) With the help of a labelled circuit diagram explain the use of P-n junction diode as a full wave rectifier. Draw the input and out put waveform

asked Jan 28, 2015 by meena.p

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a)Draw a ray diagram for formation of images of a point object by a thin double convex lens having radii of curvatures $R_1$ and $R_2$ and hence derive lens makers formula. b) Define power of a lens and give its S.I units . If a convex lens of length 50 cm is placed in contact coaxially with a concave lens of focal length 20 cm , what is the power of the combination ?

asked Jan 28, 2015 by meena.p

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An angular magnification (managing power) of 30 X is descibed using an objective of focal length $1.25\;cm$ and an eyepiece of focal length $5\;cm$ . how will you set up the compound microscope.

asked Jan 28, 2015 by meena.p

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(i)Draw the plot of binding energy per nuclear $\bigg(\large\frac{BE}{A}\bigg)$ as a function of man number A. Write two important conclusions that can be drawn regarding the nature of nuclear force. (ii) Use this graph to explain the release of energy in both processes of nuclear fusion and fission . (iii) write the basic nuclear process of neutron undergoing $\beta$- decay. Why is the detection of neutrical found very difficult ?

asked Jan 28, 2015 by meena.p

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Shreya's mother is diagnosed cancer. The attending physician suggested her for radiotherapy. He also highlighted the side effects of the treatment , also she will have t face a severe hairfall and may become bald. Shreya's mother after hearing their refused to take the treatment. (i) What would you do if you were in sherya's place? (ii) What values of life are associated with your attitude ? (iii) What are the types of radio active radiation ? Which one has the maximum penetrating power ?

asked Jan 28, 2015 by meena.p

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A long straight air- cored coil of length l has turns of radius R each . Obtain an expression for self induction of the coil.

asked Jan 28, 2015 by meena.p

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(i)How are eddy currents reduced in a metallic core ? (ii) give two uses of eddy current

asked Jan 28, 2015 by meena.p

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State kerchief's rules . How can you justify these rules ?

asked Jan 28, 2015 by meena.p

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Draw a plot showing the variation of photo electric current against the intensity of incident validation on a given photo sensitive surface.

asked Jan 28, 2015 by meena.p

1 answer

Monochromatic light of frequency $6.0 \times 10^{14}\;Hz$ is produced by a laser . The power emitted is $2.0 \times 10^{-3}\;Hz$ . Estimate the number of photos emitted per second one an average by the source.

asked Jan 28, 2015 by meena.p

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Derive an expression for the electric potential at a point along the axial line of an electric dipole.

asked Jan 28, 2015 by meena.p

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A square coil of side 10 m consists of $20$ turns and carries current of $12 A$ . The coil is suspended vertically and normal to the plane of the coil makes an angle of $30^{\circ}$ with the direction of a uniform horizontal magnetic field of magnitudes $0.80\;T$ . What is the magnitude of torque experience by the coil ?

asked Jan 28, 2015 by meena.p

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Using Biot - savart's law, derive an expression magnetic field at the center of a circular coil of radius r, having 'N' number of turns. Indicate the direction of the magnetic field.

asked Jan 28, 2015 by meena.p

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Sky waves are not used in transmitting the signals. Why ? State two factors by which the range of transmission of T.V signals can be increased.

asked Jan 28, 2015 by meena.p

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What is meant by interference of light? Write any two condition necessary for obtaining well defined and sustained interference pattern of light.

asked Jan 28, 2015 by meena.p

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Draw the logic circuit of a $NAND$ gate and wite its truth table.

asked Jan 28, 2015 by meena.p

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Which semiconductor her more mobility p- type or n-type ? Explain

asked Jan 28, 2015 by meena.p

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What are optical fibres ? give these applications of these fibres.

asked Jan 28, 2015 by meena.p

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