Recent questions in Physics

In a region of constant potential

asked Jan 3, 2017 by meena.p

1 answer

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

1 answer

Figure shows two identical capacitors $C_1$ and $C_2$ , each of $2 \mu F$ capacitance , connected to a battery of $5\;V$ . initially switch 'S' is closed . After some times S is left open and dielectric slabs of dielectric constant $K=5$ are inserted to fill completely the space between the plates of the two capacitors . How will the charge and potential difference between the plates of the capacitors be affected after the slab are inserted ?

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

Equipotential surfaces

asked Jan 3, 2017 by meena.p

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Consider a uniform electric field in the Z direction . The potential is a constant

asked Jan 3, 2017 by meena.p

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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

An electrical technician requires a capacitance of $2 \mu F$ in a circuit across a potential difference of $1\; kV$ . A large number of $1\; \mu F$ capacitors are available to him each of which can withstand a potential difference of not more than $400\; V$ . Suggest a possible arrangement that requires the minimum number of capacitors.

asked Jan 3, 2017 by meena.p

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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

A spherical capacitor consists of two concentric spherical conductors, where outer and inner radii are $r_1$ and $r_2$ respectively as shown in the figure.The capacitance of the spherical capacitor is

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

Calculate the potential at a point P due to a charge of $4 × 10^{–7}\;C$ located $9\; cm$ away.

asked Jan 3, 2017 by meena.p

1 answer

If one of the two electrons of a $H_2$ molecule is removed, we get a hydrogen molecular ion$ find potential energy of system.

asked Jan 3, 2017 by meena.p

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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

1 answer

In a hydrogen atom, the electron and proton are bound at a distance of about $0.53 \dot{A}$ : What is the minimum work required to free the electron, given that its kinetic energy in the orbit is half the magnitude of potential energy obtained ?

asked Jan 2, 2017 by meena.p

1 answer

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

A spherical conducting shell of inner radius $r_1$ and outer radius $r_2$ has a charge Q. Is the electric field inside a cavity (with no charge) zero, even if the shell is not spherical, but has any irregular shape? Explain.

asked Jan 2, 2017 by meena.p

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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

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 cylindrical capacitor has two co-axial cylinders of length $15\; cm$ and radii $1.5\; cm$ and $1.4\; cm$ . The outer cylinder is earthed and the inner cylinder is given a charge of $3.5\; \mu C$ . Determine the capacitance of the system and the potential of the inner cylinder. Neglect end effects (i.e., bending of field lines at the ends).

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

A small sphere of radius $r_1$ and charge $q_1$ is enclosed by a spherical shell of radius $r_2$ and charge $q_2$ . Show that if $q_1$ is positive, charge will necessarily flow from the sphere to the shell (when the two are connected by a wire) no matter what the charge $q_2$ on the shell is.

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

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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

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 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

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

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

If each diode in the figure has a forward bias resistance of $25\;\Omega$ and infinite resistance in reverse bias , What will be the values of the current $I_1, I_2, I_3$ and $I_4$ ?

asked Jan 2, 2017 by meena.p

1 answer

A zener of power rating 1W is to be used as a voltage regulator . If Zener has a breakdown of $5V$ and it has to regulate the voltage which fluctuated between $3\;V$ and $7\;V$ , What should be the value of $R_s$ for Safe operation .

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

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

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