Recent questions in Physics

If a body is charged by rubbing it , its weight

asked Jan 29, 2014 by yamini.v

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A point charge q=12.5 $\mu $C is placed at origin . Find the electric field vector at the point $\;(4 , 3)$ .

asked Jan 29, 2014 by yamini.v

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Three point charges of each of charge q are placed on three vertices of a square of side "l" meter . Find the magnitude of electric field at the centre of the square .

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Identify the correct statement about the charges $\;q_{1} \;and\; q_{2}$

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At what separation should two equal charges 1.0 C be placed so that the force between then equals the weight of a 25 kg person ?

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Units of electric flux are

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The following figure has two NOT gates and a NOR. What does it represent?

asked Jan 29, 2014 by meena.p

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When the separation between two charges is increased the electric potential energy of the charges

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Which of the gate is represented by

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What is the total charge on 75.0 kg of electrons ?

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How many NAND gates are used to form an AND gate

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How many electrons must be removed from a piece of metal to give it a positive charge of $\;1\times10^{-7} \;C\;?$

asked Jan 29, 2014 by yamini.v

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Truth table given below represents

asked Jan 28, 2014 by meena.p

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The following logic symbol represents

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For a given transistor, the value of the forward transfer ratio $\beta =50$. Calculatethe ratio of change in collector current to the change in emitter current.

asked Jan 28, 2014 by meena.p

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WHich of the following best describes the output of a full wave rectifier:

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The emitter current in a transistor is $ 1mA$ If $\alpha =0.95$ value of base current is :

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The transconductance of a transistor used as an amplifier in common emitter mode is $0.1 \;mho.$ When a signal of 10 mv is added to base emitter voltage change in collector current is

asked Jan 28, 2014 by meena.p

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Given $\Delta V_{BE} = $ potential difference across base emitter, $\Delta I_C = $ change in collector current, $\Delta I_B = $ change in the base current and $\Delta R_{BE} = $ change in base emitter resistance, which of the following best represents transconductance $g_m$.

asked Jan 28, 2014 by meena.p

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In a p-n function diode a input signal is applied as shown. The output across $R_L$ is

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Which of the following quantities cannot be zero on an average for the molecules of an ideal gas in equilibrium condition?

asked Jan 28, 2014 by balaji.thirumalai

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Which of the following relations hold true for a monatomic gas?

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In a transistor the level of doping for the three region is different . In the order of decreasing doping level,

asked Jan 28, 2014 by meena.p

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The specific heat of a gas:

asked Jan 28, 2014 by balaji.thirumalai

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Under the conditions when no bias is applied across a p-n junction

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Which of the following is used to produce ratio waves of constant amplitude

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Keeping the volume constant and increasing the temperature, which of the following will hold true?

asked Jan 28, 2014 by balaji.thirumalai

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When p end of P-n junction is connected to positive terminal of the battery and N end to negative terminal , the p-n junction behaves like

asked Jan 28, 2014 by meena.p

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Which of the following statement is incorrect ?

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For approximately ten times increase in conductivity of a semiconductor the impurity to be added is of the order of

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The valancy of impurity atom added to silicon to make it P type is

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The forbidden gap in energy bands in silicon is order of

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Which is doped heaviest in a transistor

asked Jan 28, 2014 by meena.p

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The average translational kinetic enegry of Oxygen molecules (molecular weight of $O_2$ is 32) at a particlular temperature is 0.032eV. What is the average translational kinetic energy of $N_2$ molecules (molecular weight is 28) at the same temperature

asked Jan 28, 2014 by balaji.thirumalai

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A change of 10 mA in the emitter current produces a change of 7.5 mA in collector current in a transistor . What should be change in base current to produce the same change in collector current.

asked Jan 28, 2014 by meena.p

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A vessel is filled with an ideal gas at 76 cm of Hg (mercury). The mass of gas is increased by 25% by introducing more gas at the same temperature. What is the resultant pressure of Hg in cm?

asked Jan 28, 2014 by balaji.thirumalai

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The energy density of an ideal monoatomic gas is equal to:

asked Jan 28, 2014 by balaji.thirumalai

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The $x$-components of velocity of some particles (in $km/s$) are $6,4,2,0,-2,-4,-6$. The root-mean-square (rms) velocity calculated from these data (in $km/s$) is nearest to?

asked Jan 28, 2014 by balaji.thirumalai

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A given sample of ideal gas is made to undergo a process in which the temperature decreases by 10% and the pressure decreases by 8%. By what % does the volume change?

asked Jan 28, 2014 by balaji.thirumalai

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A transistor in common emitted mode the load resistance is $2k \Omega$ and the current gain $\beta =50,$ What is the power if input resistance is $500 \Omega$

asked Jan 28, 2014 by meena.p

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When negative voltage feedback is applied to an amplifier of gain 150, the overall gain falls to 15. Find the fraction of the output that is feedback to the input.

asked Jan 28, 2014 by meena.p

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In an amplifier, negative feedback is introduced with feedback fraction $\beta =0.01$. If voltage given with out negative feed back. is $2500$ what is voltage gain with negative feed back.

asked Jan 28, 2014 by meena.p

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In an n-p-n transistor only $3 \%$ of the charge carriers are allerved to recombine in the base region. The value of $ \alpha$ is

asked Jan 28, 2014 by meena.p

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What is the emitter current $I_E$ in a transfer where base current $I_B$ is $20 \mu A$ and $\beta =40$

asked Jan 28, 2014 by meena.p

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What is the output resistance, When we observe in a common emitter circuit the collector current increase from $9.5 \;mA\;to 10\;mA$ When the collector voltage increase from $2.5 \;to \;6v$ When base current is kept constant .

asked Jan 28, 2014 by meena.p

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In a common base amplifier current gain is $0.96$ and emitter current is $7.2\;mA$. The base current is

asked Jan 28, 2014 by meena.p

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In a common emitter transistor the current gain is 80. What is change in collector current , when change in base current is $250 \mu A$

asked Jan 28, 2014 by meena.p

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In the use of transistor as an amplifier $I_f \alpha =\large\frac{I_c}{I_e}$ and $\beta =\large\frac{I_c}{I_b}$ where $I_c$- collector current $I_b$- base current $I_e$- emitter current then

asked Jan 28, 2014 by meena.p

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In a transistor collector base is biased and emitter base is _ biased.

asked Jan 28, 2014 by meena.p

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An electron enters the p-n junction from the n-side with a velocity of $5 \times 10^5 m/s$ . If the depletion region is $5 \times 10^{-7} m/s$ wide and the potential barrier is $0.5 V$ What will be its speed When it enters P side ?

asked Jan 28, 2014 by meena.p

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