Recent questions tagged ncert

Three capacitors of capacitances $2pF, 3pF$ and $4pF$ are connected in parallel. Determine the charge on each capacitor if the combination is connected to a $100\; V$ supply.

asked Jan 3, 2017 by meena.p

1 answer

Three capacitors each of capacitance $9 \;pF$ are connected in series. What is the potential difference across each capacitor if the combination is connected to a $120\; V$ supply?

asked Jan 3, 2017 by meena.p

1 answer

A $900 \;pF$ capacitor is charged by $100\; V$ battery. How much electrostatic energy is stored by the capacitor?

asked Jan 3, 2017 by meena.p

1 answer

A system consisting of two charges $7 \mu C$ and $–2 \mu C$ placed at $(–9 cm, 0, 0)$ and $(9 cm, 0, 0)$ respectively

asked Jan 3, 2017 by meena.p

1 answer

Determine the electrostatic potential energy of a system consisting of two charges $7 \mu C$ and $–2 \mu C$ (and with no external field) placed at $(–9 cm, 0, 0)$ and $(9 cm, 0, 0)$ respectively.

asked Jan 3, 2017 by meena.p

1 answer

Determine the electrostatic potential energy of a system consisting of two charges $7 \mu C$ and $–2 \mu C$ (and with no external field) placed at $(–9 cm, 0, 0)$ and $(9 cm, 0, 0)$ respectively.mple 2.5 (a) Determine the electrostatic potential energy of a system consisting of two charges 7 µC and –2 µC (and with no external field) placed at (–9 cm, 0, 0) and (9 cm, 0, 0) respectively.Suppose that the same system of charges is now placed in an external electric field $E = A (1/r^2); A = 9 \times 10^5 C m^{–2}$. What would the electrostatic energy of the configuration be?

asked Jan 2, 2017 by meena.p

1 answer

Determine the electrostatic potential energy of a system consisting of two charges $7 \mu C$ and $–2\;\mu C$ (and with no external field) placed at $(–9 cm, 0, 0)$ and $(9 cm, 0, 0)$ respectively.

asked Jan 2, 2017 by meena.p

1 answer

A $600 \;pF$ capacitor is charged by a $200\; V$ supply. It is then disconnected from the supply and is connected to another uncharged $600 \;pF$ capacitor. How much electrostatic energy is lost in the process?

asked Jan 2, 2017 by meena.p

1 answer

$A 12 \;pF$ capacitor is connected to a $50\;V$ battery. How much electrostatic energy is stored in the capacitor?

asked Jan 2, 2017 by meena.p

1 answer

In a parallel plate capacitor with air between the plates, each plate has an area of $6 \times 10^{−3} m^2$and the distance between the plates is $3\; mm$. Calculate the capacitance of the capacitor. If this capacitor is connected to a $100\; V$ supply, what is the charge on each plate of the capacitor?

asked Jan 2, 2017 by meena.p

1 answer

Three capacitors of capacitances $2pF, 3pF$ and $4pF$ are connected in parallel. What is the total capacitance of the combination?

asked Jan 2, 2017 by meena.p

1 answer

Three capacitors each of capacitance $9 \;pF$ are connected in series. What is the total capacitance of the combination?

asked Jan 2, 2017 by meena.p

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A parallel plate capacitor with air between the plates has a capacitance of $8 pF (1pF = 10^{−12} F)$. What will be the capacitance if the distance between the plates is reduced by half, and the space between them is filled with a substance of dielectric constant $6$?

asked Jan 1, 2017 by meena.p

1 answer

Two charges $2 \mu C$ and $−2 \mu C$ are placed at points A and B 6 cm apart. (a) Identify an equipotential surface of the system. (b) What is the direction of the electric field at every point on this surface?

asked Jan 1, 2017 by meena.p

1 answer

A regular hexagon of side $10\; cm$ has a charge $5 \;\mu C$ at each of its vertices. Calculate the potential at the centre of the hexagon.

asked Jan 1, 2017 by meena.p

1 answer

Truth table for the given circuit is

asked Jan 1, 2017 by meena.p

2 answers

Write the truth table for the circuit below :

asked Jan 1, 2017 by meena.p

1 answer

Write the logical operation for the given circuit .

asked Jan 1, 2017 by meena.p

1 answer

Write the truth table for the circuit given

asked Jan 1, 2017 by meena.p

1 answer

Write the logic operation for the below circuit :

asked Jan 1, 2017 by meena.p

1 answer

write the truth table for the circuit below :

asked Jan 1, 2017 by meena.p

1 answer

Identify the exact logic operation carried out by the circuit below

asked Jan 1, 2017 by meena.p

1 answer

write the truth table for a NAND gate for the fig given

asked Jan 1, 2017 by meena.p

1 answer

An $emf$ is produced in a coil, which is not connected to an external voltage source. This can be due to
(a) The coil being in a time varying magnetic field
(b) The coil moving in a time varying magnetic field
(c) The coil moving in a constant magnetic field
(d) The coil is stationary is externally spatially varying magnetic field, which does not change with time.

asked Dec 31, 2016 by priyanka.c

1 answer

In a npn transistor circuit, the collector current is $10\;mA$. If $95\%$ of the electrons emitted reach the collector, Which of the following statements are true ?

asked Dec 31, 2016 by meena.p

1 answer

Evaluate the induced $emf$ in the loop if the wire carries a current of 50A and the loop has an instantaneous velocity $v = 10 m/s$ at the location $x= 0.2 m,$ as shown, Take $a = 0.1$ and assume that the loop has a large resistance.

asked Dec 31, 2016 by priyanka.c

1 answer

Obtain an expression for the mutual inductance between a long straight wire and a square of side a as shown in the figure .

asked Dec 31, 2016 by priyanka.c

1 answer

An air-cored solenoid with length 30cm, area of cross section $25 cm^2$ and number of turns 500, carries a current of 2.5A. The current is suddenly switched off in a brief time of $10^{-3}S.$ How much is the average back emf induced across the ends of the open switch in the circuit ? Ignore the variation in magnetic field near the ends of the solenoid ?

asked Dec 31, 2016 by priyanka.c

1 answer

Write the logic operation for the circuit below :

asked Dec 31, 2016 by meena.p

1 answer

Identify the logic operation :

asked Dec 31, 2016 by meena.p

1 answer

Identify the logic operation :

asked Dec 31, 2016 by meena.p

1 answer

How much power is dissipated as heat in the closed circuit ? What is the source of this power ?

asked Dec 31, 2016 by priyanka.c

1 answer

You are given a circuit . Name the output gate

asked Dec 31, 2016 by meena.p

1 answer

Figure shows a metal rod PQ resting on the smooth rail AB and positioned between the poles of a permanent magnet. The rail, the rod and the magnetic field are in three mutual perpendicular directions. A galvanometer G connects the rails through a switch K. Length of the rod = 15 cm, B = 0.50 T, resistance of the closed loop containing the rod = $9.0 m \Omega$. Assume the field to be uniform.
What is the induced emf in the moving rod if the magnetic field is parallel to the rails instead of being perpendicular?

asked Dec 31, 2016 by priyanka.c

1 answer

You are given a circuit . Name the output gate

asked Dec 31, 2016 by meena.p

1 answer

Figure shows a metal rod PQ resting on the smooth rail AB and positioned between the poles of a permanent magnet. The rail, the rod and the magnetic field are in three mutual perpendicular directions. A galvanometer G connects the rails through a switch K. Length of the rod = 15 cm, B = 0.50 T, resistance of the closed loop containing the rod = $9.0 m \Omega$. Assume the field to be uniform.

How much power is required at the same speed, to keep the rod moving at the same speed. (=12 cm/s) when k is closed ?

asked Dec 31, 2016 by priyanka.c

1 answer

In p-n junction diode , the current I , can be expressed $I= I_0 exp \bigg[ \large\frac{eV}{K_{B}T}-1 \bigg]$ Where $I_0$ is called the satiation current , V is the voltage across the dicode and in positive for forward bias and negative for reverse bias and I is the current through the dicode , $K_B$ is the BoHZmann constant $(8.6 \times 10^{-5}e^v/k)$ and T is the absolute temperature . If for a given diode $I_0 = 5 \times 10^{-12}A $ and $T=300\;K$ , then what will be the increase in the current if the voltage across the diode is increased to $0.7\;A$?what will be the Dynamic resistance

asked Dec 31, 2016 by meena.p

1 answer

Figure shows a metal rod PQ resting on the smooth rail AB and positioned between the poles of a permanent magnet. The rail, the rod and the magnetic field are in three mutual perpendicular directions. A galvanometer G connects the rails through a switch K. Length of the rod = 15 cm, B = 0.50 T, resistance of the closed loop containing the rod = $9.0 m \Omega$. Assume the field to be uniform.

what is the retarding force on the rod when k is closed ?

asked Dec 31, 2016 by priyanka.c

1 answer

Figure shows a metal rod PQ resting on the smooth rail AB and positioned between the poles of a permanent magnet. The rail, the rod and the magnetic field are in three mutual perpendicular directions. A galvanometer G connects the rails through a switch K. Length of the rod = 15 cm, B = 0.50 T, resistance of the closed loop containing the rod = $9.0 m \Omega$. Assume the field to be uniform.

With k open and the rod moving uniformly, there is no net force on the electrons in the rod PQ even though they do experience magnetic force due to the motion of the rod. Explain.

asked Dec 31, 2016 by priyanka.c

1 answer

Figure shows a metal rod PQ resting on the smooth rail AB and positioned between the poles of a permanent magnet. The rail, the rod and the magnetic field are in three mutual perpendicular directions. A galvanometer G connects the rails through a switch K. Length of the rod = 15 cm, B = 0.50 T, resistance of the closed loop containing the rod = $9.0 m \Omega$. Assume the field to be uniform.

Is there an excess charge built up at the ends of rods, when k is open ? What if k is closed ?

asked Dec 31, 2016 by priyanka.c

1 answer

Figure shows a metal rod PQ resting on the smooth rail AB and positioned between the poles of a permanent magnet. The rail, the rod and the magnetic field are in three mutual perpendicular directions. A galvanometer G connects the rails through a switch K. Length of the rod = 15 cm, B = 0.50 T, resistance of the closed loop containing the rod = $9.0 m \Omega$. Assume the field to be uniform.

Suppose K is open and the rod is moved with a speed of 12cm/s in the direction shown. Give the polarity and magnitude of the induced $emf$.

asked Dec 31, 2016 by priyanka.c

1 answer

It is desired to measure the magnitude of field between the poles of a powerful loud speaker magnet. A small flat search coil of area $2cm^2$ with closely wound turns, is positioned normal to the field direction and then quickly snatched out of the field region. Equivalently one can give it a quick $90^{\circ}$ turns to bring its plane parallel to the field direction. The total change flown in the coil (measured by a ballistic galvanometer connected to coil) is 7.5mc. The combined resistance of the coil and the galvanometer $0.50 \Omega$. Estimate the field strength of magnet.

asked Dec 30, 2016 by priyanka.c

1 answer

A square loop of side 12cm with its sides parallel to X and Y axes is moved with a velocity of 8 cm/s in the positive X-direction in an environment containing a magnetic field in the positive Z-direction. The field is neither uniform in space nor constant in time. It has a gradient of $10^{-3}$T/cm along the negative X-direction (that is it increases by $10^{-3}$T/cm as one moves in the negative X-direction) and it is decreasing in time at the rate of $10^{-3} $ T/S. Determine the direction and magnitude of the induced current in the loop if its resistance is $4.50 m\Omega$

asked Dec 30, 2016 by priyanka.c

1 answer

Suppose a rectangular loop of sides 8cm and 2cm with a small cut is stationary but the current feeding the electromagnet that produces the magnetic field is gradually reduced so that the field decreases from its initial value of 0.3T at the rate of 0.02T/S. If the cut is joined and the loop has a resistance of 1.6$ \Omega$, how much power is dissipated by the loop as heat? What is the source of this power ?

asked Dec 30, 2016 by priyanka.c

1 answer

In p-n junction diode , the current I , can be expressed $I= I_0 exp \bigg[ \large\frac{eV}{K_{B}T}-1 \bigg]$ Where $I_0$ is called the satiation current , V is the voltage across the dicode and in positive for forward bias and negative for reverse bias and I is the current through the dicode , $K_B$ is the Boltzmann constant $(8.6 \times 10^{-5}e^v/k)$ and T is the absolute temperature . If for a given diode $I_0 = 5 \times 10^{-12}A $ and $T=300\;K$ , then what will be the increase in the current if the voltage across the diode is increased to $0.7\;A$?

asked Dec 30, 2016 by meena.p

1 answer

In p-n junction diode , the current I , can be expressed $I= I_0 exp \bigg[ \large\frac{eV}{K_{B}T}-1 \bigg]$ Where $I_0$ is called the satiation current , V is the voltage across the dicode and in positive for forward bias and negative for reverse bias and I is the current through the dicode , $K_B$ is the Boltzmann constant $(8.6 \times 10^{-5}e^v/k)$ and T is the absolute temperature . If for a given diode $I_0 = 5 \times 10^{-12}A $ and $T=300\;K$ , then what will be the forward current at a forward voltage of $0.6\;V$?

asked Dec 30, 2016 by meena.p

1 answer

In an intrinsic semiconductor the energy gap $E_g$ is $1.2\;ev$ . It hole mobility and independent of temperature . What is the ratio between conductivity at $600\;k$ and $300\;k$ Assume that the temperature dependence intrinic concentration $n_i$ is given by $n_i = n_0 exp\bigg(\large\frac{-Eg}{2K_b t}\bigg)$, Where $n_o$ is a Constant and $K_b= 8.62 \times 10^{-5} ev/K$

asked Dec 30, 2016 by meena.p

1 answer

A jet plane is travelling towards west at a speed of $1800\; km/hr$. What is the voltage difference developed between the ends of the wing having a span of 25m, if the earth's magnetic field at the location has a magnitude of $5 \times 10^{-4} T$ and the dip angle is $30^{\circ}$

asked Dec 30, 2016 by priyanka.c

1 answer

The number of silicon atoms per $m^3$ is $5 \times 10^{28}$ This is doped simultaneously with $ 5 \times 10^{22}$ atom per $m^3$ of and $ 5 \times 10^{26}$ per $m^3 $ atoms of indium . Calculate the number of electrons and holes . Given that $n_i=1.5 \times 10^{16}\;m^{-3}$. material n -type or p type

asked Dec 30, 2016 by meena.p

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A pair of adjacent coils have a mutual inductance of 1.5 H. If the current in one is changed from $0 \; to\; 20 A$ is $0.5 S$ , what is the change of flux with the other coil.

asked Dec 30, 2016 by priyanka.c

1 answer

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