Recent questions tagged medium

Self reduction is possible in which of following :

asked Oct 4, 2018 by meena.p

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$2\sin ^2\large\frac{3\pi}{4}$$+2\cos^2\large\frac{\pi}{4}$$+2\sec^2\large\frac{\pi}{3}$ =

asked Jul 3, 2018 by pady_1

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Which of the following correctly denotes the catalyst and promoter used in Haber's process for manufacture of ammonia, respectively?

asked Feb 15, 2017 by meena.p

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A parallel plate capacitor is made of two dielectric blocks in series. One of the blocks has thickness $d_1$ and dielectric constant $k_1$ and the other has thickness $d_2$ and dielectric constant $k_2$ as shown in Fig. This arrangement can be thought as a dielectric slab of thickness $d (= d_1+d_2)$ and effective dielectric constant k. The k is

asked Jan 3, 2017 by meena.p

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A parallel plate capacitor with air between the plates has a capacitance of $8\;pF$ . The separation between the plates is now reduced by half and the space between them is filled with a medium of dielectric constant 5. Calculate the value of capacitance of the capacitor in the second case .

asked Jan 3, 2017 by meena.p

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A test charge q is moved without a acceleration from A to C along the path from A to B and then from B to C in electric field E as shown in the figure . Calculate the potential difference between A and C

asked Jan 3, 2017 by meena.p

1 answer

Two charges $2\mu C$ and $-2 \mu C$ are placed at points A and B, 5cm apart . Depict an equipotential surface of the system

asked Jan 3, 2017 by meena.p

1 answer

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 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

Two charged conducting spheres of radii a and b are connected to each other by a wire. What is the ratio of electric fields at the surfaces of the two spheres? Use the result obtained to explain why charge density on the sharp and pointed ends of a conductor is higher than on its flatter portions.

asked Jan 3, 2017 by meena.p

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In a hydrogen atom, the electron and proton are bound at a distance of about 0.53 Å: Estimate the potential energy of the system in eV, taking the zero of the potential energy at infinite separation of the electron from proton.

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.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

The plates of a parallel plate capacitor have an area of $90\; cm^2$ each and are separated by $2.5\; mm$. The capacitor is charged by connecting it to a $400\; V$ supply.How much electrostatic energy is stored by the capacitor?

asked Jan 2, 2017 by meena.p

1 answer

A $4 \mu F$ capacitor is charged by a $200\; V$ supply. It is then disconnected from the supply, and is connected to another uncharged $2 \mu F$ capacitor. How much electrostatic energy of the first capacitor is lost in the form of heat and electromagnetic radiation?

asked Jan 2, 2017 by meena.p

1 answer

A spherical capacitor has an inner sphere of radius 12 cm and an outer sphere of radius 13 cm. The outer sphere is earthed and the inner sphere is given a charge of $2.5 \mu C$. The space between the concentric spheres is filled with a liquid of dielectric constant $32$. What is the potential of the inner sphere?

asked Jan 2, 2017 by meena.p

1 answer

A spherical capacitor has an inner sphere of radius 12 cm and an outer sphere of radius 13 cm. The outer sphere is earthed and the inner sphere is given a charge of $2.5 \mu C$. The space between the concentric spheres is filled with a liquid of dielectric constant $32$. Determine the capacitance of the capacitor.

asked Jan 2, 2017 by meena.p

1 answer

A parallel plate capacitor is to be designed with a voltage rating $1\; kV$, using a material of dielectric constant $3$ and dielectric strength about $10^7\; Vm^{−1}$. (Dielectric strength is the maximum electric field a material can tolerate without breakdown, i.e., without starting to conduct electricity through partial ionisation.) For safety, we should like the field never to exceed, say $10 \%$ of the dielectric strength. What minimum area of the plates is required to have a capacitance of $50\; pF$?

asked Jan 2, 2017 by meena.p

1 answer

In a Van de Graaff type generator a spherical metal shell is to be a $15 × 10^6\; V$ electrode. The dielectric strength of the gas surrounding the electrode is $5 × 10^7 \;Vm^{−1}$. What is the minimum radius of the spherical shell required?

asked Jan 2, 2017 by meena.p

1 answer

Explain what would happen if in the capacitor given in 3 mm thick mica sheet (of dielectric constant = 6) were inserted between the plates C=1.771 x 10^-11 F, after the supply voltage of 100 V is was disconnected

asked Jan 2, 2017 by meena.p

1 answer

Explain what would happen if in the capacitor given in 3 mm thick mica sheet (of dielectric constant = 6) were inserted between the plates, While the voltage supply remained connected.

asked Jan 2, 2017 by meena.p

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A spherical conductor of radius $12\; cm$ has a charge of $1.6 \times 10^{−7}\;C$ distributed uniformly on its surface. What is the electric field at a point 18 cm from the center of the sphere ?

asked Jan 2, 2017 by meena.p

1 answer

A spherical conductor of radius $12\; cm$ has a charge of $1.6 \times 10^{−7}\;C$ distributed uniformly on its surface. What is the electric field just outside the sphere ?

asked Jan 2, 2017 by meena.p

1 answer

A spherical conductor of radius $12\; cm$ has a charge of $1.6 \times 10^{−7}\;C$ distributed uniformly on its surface. What is the electric field inside the sphere ?

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

1 answer

A charge of $8\; mC$ is located at the origin. Calculate the work done in taking a small charge of $−2 \times 10^{−9}\; C$ from a point $P (0, 0, 3 \;cm)$ to a point $Q (0, 4 \;cm, 0)$, via a point $R (0, 6cm, 9 cm)$.

asked Jan 2, 2017 by meena.p

1 answer

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

In the circuit shown in the figure , if the diode forward voltage is $0.3\;V$ , the voltage difference between A and B is

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

A solenoid is connect to a battery so that a steady current flows through it. If an iron core is inserted into the solenoid, will the current increases or decreases ? Explain ?

asked Dec 31, 2016 by priyanka.c

1 answer

A wire in the form of a tightly wound solenoid is connected to DC source, and carries a current. If the coil is stretched so that spiral coil, will the current increases or decreases ? Explain.
(a) the current drawn from the d.c source increases
(b) the current drawn from d.c source decreases
(c) the current drawn first increases and then decreases
(d) the current drawn first decreases and then increases

asked Dec 31, 2016 by priyanka.c

1 answer

Consider a magnet surrounded by a wire with an on/off switch as shown in the fig. If the switch is thrown from the off position (open circuit) to the on position (closed circuit) will a current flow in the circuit ? Explain.
(a) Yes
(b) No
(c) Cannot be determine
(d) information not sufficient

asked Dec 31, 2016 by priyanka.c

1 answer

There are two coils A and B. A current starts flowing in B, the coil A is made to rotate about a vertical axis as shown in the fig. No current flows in B if A is at rest. The current in the coil A, when the current in B (at t = 0) is counter clockwise and the coil A is as shown at this instant t= 0 is
(a) constant current clockwise
(b) varying current clockwise
(c) varying current clockwise<br> (d) constant current counter clockwise.

asked Dec 31, 2016 by priyanka.c

1 answer

Figure shows some equipotential lines distributed in space .A charged object is moved from point A and point B.

asked Dec 31, 2016 by meena.p

1 answer

There are two coils A and B as shown in fig. A current starts flowing in B as shown, when A is moved towards B and stops when A stops moving. The current in A is counter-clockwise. B is kept stationary when A moves. We can infer that
(a) there is a constant current in the anticlockwise direction in A (b) there is a varying current in A
(c) there is no current in A
(d) there is a constant current in the counter clockwise direction in A

asked Dec 31, 2016 by priyanka.c

1 answer

A cylindrical bar magnet is rotated about its axis, as shown in fig. A wire is connected from the axis and is made to touch the cylindrical surface through a contact. Then
(a) a direct current flows in the ammeter A
(b) an alternating sinusoidal current flows through the ammeter A with a time period $T= \frac{2T}{w}$
(c) no current flows through the ammeter A
(d) a time varying non-sinusoidal current flows through the ammeter A

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

A loop, made of straight edges has six corner at A(0, 0, 0), B(L, 0, 0), C(L, L, O), D(O, L,O), E(O, L, L) and F (0, 0, L). A magnetic field $B = B_o(\hat{i} + \hat{k})T$ is present in the region.
The flux passing through the loop ABCDEFA (in that order) is $(a)B_oL^2Wb$ $(b)2B_oL^2Wb$ $(c)\sqrt 2B_oL^2Wb$ $(d)4B_oL^2Wb$

asked Dec 31, 2016 by priyanka.c

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

A $220\;V$ A.C supply in connected between points A and B as shown in the figure . What will be the potential difference V across the capacitor ?

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

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

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

A p-n photo diode is fabricated from a semi - conductor with a band gap of $2.5 \;ev$. It can detect a signal of wavelength

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.

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

The voltage gain of an amplifier with $9\%$ negative feed back is $10$. The voltage gain with out feedback will be

asked Dec 31, 2016 by meena.p

1 answer

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