Recent questions in Physics

An electron losely bound to the impurity of a doped semiconductor is able to jump to the conducting band because of thermal collision at temperature T k. If the impurity level is 15 mev below the conducting band, calculate the temperature.

asked Jan 28, 2014 by meena.p

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What is the resistivity of n-type semiconductors given: Density of conducting electrons $=8 \times 10^{13} /cc$; Density of holes $=5 \times 10^{12} /cc$ mobility of electron $=2.3 \times 10^4 cm^2 /v-s$ mobility of holes $=100 cm^2 /v-s$

asked Jan 28, 2014 by meena.p

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Find the current through resistance in the circuit.

asked Jan 28, 2014 by meena.p

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Let Potential at A and B be $V_A$ and $V_B$ respectively . In the given circuit. If the effective resistance is found to be $5 \Omega$ Then

asked Jan 28, 2014 by meena.p

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What is reading in ammeter $A_1$ and $A_2$ in given circuit.

asked Jan 27, 2014 by meena.p

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In the given diagram resistance of each diode in forward bias is zero and infinity in reverse bias . If a 2V battery is connected as shown in circuit What is the effective current.

asked Jan 27, 2014 by meena.p

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When a 10v battery is connected as shown in the circuit what is the potential difference across A and B ?

asked Jan 27, 2014 by meena.p

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The diode connected in forward bias has zero resistance and if connected in reverse biase has infinity resistance Find the effective resistance across A and B the given circuit.

asked Jan 27, 2014 by meena.p

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What is current and voltage across the diode in The given circuit given drift current is $ 2 \times 10^{-3}A$

asked Jan 27, 2014 by meena.p

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In a p-n junction hole with kinetic energy 250 mev approaches the junction from m-side . The potential barrier is 200 mev. What will be its kinetic energy when it crosses the junction .

asked Jan 27, 2014 by meena.p

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In Germanium it is found that concentration of conducting electron is $3 \times 10^{19} $ per cubic meter. When Phosphorus impurity is doped the concentration of conducting electron increases to $2 \times 10^{23}$ per cubic meter. If product of hole concentration and conducting electron is independent of amount of impurity find the hole concentration in doped Germanium.

asked Jan 27, 2014 by meena.p

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In the given circuit, potential barriers developed across diode is $0.5 v$ . Find the current in the circuit.

asked Jan 27, 2014 by meena.p

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Which of the following is reverse biased diode.

asked Jan 27, 2014 by meena.p

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In LEDs one can see emitted light to because

asked Jan 27, 2014 by meena.p

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Avalanche breakdown is due to

asked Jan 27, 2014 by meena.p

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Zener breakdown occurs:

asked Jan 27, 2014 by meena.p

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The approximate ratio of resistance in forward bias of p-n junction is

asked Jan 27, 2014 by meena.p

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The conduction band of a solid is partially filled at OK.Then the solid is

asked Jan 27, 2014 by meena.p

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Electrical conductivity of pure germanium can be increased by 1) increasing the temperature 2) doping with donor impurities 3) radiation with ultra violet rays. 4) doping with acceptor impurities

asked Jan 27, 2014 by meena.p

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In a p-n junction the depletion region is $200 nm$ wide and a electric field of $10^6 vm^{-1}$ exists in it. What is the minimum kinetic energy of conducting electron to diffuse through the barriers.

asked Jan 27, 2014 by meena.p

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In pure semiconductor number of conducting electrons is $5 \times 10^{20} $ per cubic meter. How many holes are there in $1 cm^3$ of the same semiconductor.

asked Jan 27, 2014 by meena.p

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The impurity atom with which pure silicon can be doped to make p-type semiconductors are

asked Jan 27, 2014 by meena.p

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What is intensity of electric field in the depletion region of which $2.5 \times 10^{-7} m$ if the potential barrier is $0.50 v$

asked Jan 27, 2014 by meena.p

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A p type semiconductor has acceptor level of 50 mev above the valance band. Find the maximum wave length of light which can create a hole.

asked Jan 27, 2014 by meena.p

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The diffusion current in p-n junction is due to

asked Jan 27, 2014 by meena.p

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Electronic conduction to in a semiconductor takes place due to

asked Jan 27, 2014 by meena.p

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Which of the following are incorrect statements about a transistor?

asked Jan 27, 2014 by meena.p

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The reverse bias in p-n junction

asked Jan 27, 2014 by meena.p

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In p-n junction diode : the depletion zone has

asked Jan 27, 2014 by meena.p

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Semi conductors doped with donor atoms have majority carriers as

asked Jan 27, 2014 by meena.p

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Fermi energy is

asked Jan 27, 2014 by meena.p

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Which of the following is true about semiconductors?

asked Jan 27, 2014 by meena.p

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A plate of thickness x made of refractive index $\mu $ is placed in front of one of the slits in a double slit experiment. What should be minimum thickness x . so that the central maxima turns to fringe with minimum intensity

asked Jan 24, 2014 by meena.p

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Equi convex lens is placed such that optic axis coincides with the x-axis, position of object is $(-40 \;cm, 1 \;cm) $ and position of image $(50 \;cm, -2\;cm) $ where is the lens located

asked Jan 24, 2014 by meena.p

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A ray of light is incident on a prism of refractive index $\mu =\sqrt 2$ It is found that the deviation caused is $30^{\circ}$ The angle of prism is $60^{\circ}$ What will be the angle between the ray inside the prism and the base of the prism .

asked Jan 24, 2014 by meena.p

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A prism of refractive index $\mu =1.5 $ of vertical angle $6 ^{\circ}$ is placed in front of a mirror. A ray of light is incident normally on one of the face of the prism as shown. What is the total deviation caused by the system.

asked Jan 24, 2014 by meena.p

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Two waves have a phase difference of $\pi $. and they have light intensities I and 9I. What will be the resultant intensity .

asked Jan 24, 2014 by meena.p

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Find the width of central maxima given $\lambda = 5 \times 10^{-5}\;cm$ slit separation $d= 0.15 \;cm$ and distance between screen and slit $D= 2.1 \;m$

asked Jan 24, 2014 by meena.p

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An unpolarised light is incident on a glass plate at polarizing angle $57^{\circ}$ with the normal on a glass plane. The reflected light will be

asked Jan 24, 2014 by meena.p

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In Young's double slit experiment the distance between adjacent fringe is x and L is distance between slit and screen. If d is split separation , then wave length is

asked Jan 24, 2014 by meena.p

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An interference pattern is observed in a young 's double slit experiment in air. Now this chamber is evacuated and the same light is used we will see .

asked Jan 24, 2014 by meena.p

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Wave nature of light explains the phenomenon of

asked Jan 24, 2014 by meena.p

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A ray of light passes through four transparent media with refractive indices $\mu_1, \mu_2, \mu_3$ and $\mu_4$ as shown. The surface of all media are parallel. The emerging say CD is parallel to incident ray AB, Then ,

asked Jan 24, 2014 by meena.p

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In Lloyd's single mirror experiment A light wave emitted directly from sources s interferes with a wave reflected from a mirror M. The interference pattern is formed on the screen which is kept perpendicular to the mirror and at a distance. $D=1 m$ from the source as shown . If the sources is at a distance of 1 mm from the plane of the mirror what is the fringe width when monochromatic light of 600 nm is incident from the sources

asked Jan 24, 2014 by meena.p

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By what percentage should the volume be decreased to increase the pressure by 10% at constant temperature?

asked Jan 24, 2014 by balaji.thirumalai

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In a young's double slit experiment illuminated by monochromatic light the slit separation is $0.3\;mm$ and slit- screen separation is $1.5 \;m$. If fourth bright fringe is 1 cm from central bright fringe, the wavelength of light used is

asked Jan 24, 2014 by meena.p

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If the speed of sound in Hydrogen at NTP is equal to the speed of sound in carbon-di-oxide at $T_0$, what is the value of $T_0$? (i.e, $T = 273K$)

asked Jan 24, 2014 by balaji.thirumalai

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Sound travels with a speed $v$ in hydrogen gas at NTP. At what temperatures does carbon-di-oxide have a rms (root mean square) velocity of $2v$ (Note: $T_0 = 273K$ and $\gamma$ for $H_2 = \large\frac{7}{5}$)

asked Jan 24, 2014 by balaji.thirumalai

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In a young's double slit experiment the fringe width is $0.05\;mm$ when the distance of screen from slit is $75 \;cm$ . If the distance of screen from the slit is increased by $25 \;cm$ , the fringe width will be

asked Jan 23, 2014 by meena.p

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A slit of width 'a' is illuminated by white light. For what value of 'a' will the first minimum for red light of wavelength $\lambda =650 \;nm$ appear for $\theta =30^{\circ}$?

asked Jan 23, 2014 by meena.p

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