Recent questions in Physics

What is the largest voltage you can safely put across a resistor marked $196 \Omega -1W$

asked Jun 30, 2015 by meena.p

1 answer

Two electric lamps A and B are marked. $220\;V- 100\;w$ and $220\;V-60\;W$ Out of the two which lamp has higher resistance ?

asked Jun 30, 2015 by meena.p

1 answer

Define electrical conductivity of a conductor and give in S.I unit .

asked Jun 30, 2015 by meena.p

1 answer

Two wires of equal length one of copper and of mangain have the same resistance which wire in thicker ?

asked Jun 30, 2015 by meena.p

1 answer

Name some elements which does not obey ohm's law

asked Jun 29, 2015 by meena.p

1 answer

What are the conditions required for making a conductor as a super conductor ?

asked Jun 29, 2015 by meena.p

1 answer

A wire of resistivity $\rho$ is stretched to three times its length . What will be the new resistivity ?

asked Jun 29, 2015 by meena.p

1 answer

What is the conductance of a wire of resistance $2\;m \sigma$ ?

asked Jun 29, 2015 by meena.p

1 answer

Give the relation between drift velocity and electric field

asked Jun 29, 2015 by meena.p

1 answer

Explain why bending a wire does not affect its electrical resistance ?

asked Jun 29, 2015 by meena.p

2 answers

How will you represent a resistance of $3700 \Omega \pm 10\%$ by colour code?

asked Jun 29, 2015 by meena.p

1 answer

A carbon resistance is marked in red, green, and orange bands . What is the approximate resistance of the resistor ?

asked Jun 29, 2015 by meena.p

1 answer

There resistors $1 \Omega, 2 \Omega$ and $3 \Omega$ are combined in series . What is the total resistance of the combination ? b) If the combination is connected to a battery of emf $12\;V$ and negligible internal resistance , Obtain the potential drop across each resistors?

asked Jun 29, 2015 by meena.p

1 answer

A battery of emf $10\;v$ and internal resistance $3 \Omega$ is connected to a resistor . If the current in the circuit is $0.5\;A$ , What is the resistance of the resistor ? What is the resistance of the resistor ? What is the terminal voltage of the battery when the circuit is closed ?

asked Jun 29, 2015 by meena.p

1 answer

The storage battery of a can an ems of $12V$ .If the internal resistance of the battery is $0.4 \Omega$ What is the maximum current that can be drawn from the battery ?

asked Jun 29, 2015 by meena.p

1 answer

The resistivity of a typical insulator (eg: amber) is greater that of a metal by a factor of the order of $10^{22} /10^{23}$

asked Jun 29, 2015 by meena.p

1 answer

Alloys usually have lower/higher temperature is nearly independent of / increases rapidy with increase of temperature

asked Jun 29, 2015 by meena.p

1 answer

Alloys of metals have greater / lesser resistivity than that of their constituent metal?

asked Jun 29, 2015 by meena.p

1 answer

When electrons drift in a metal from lower to higher potential , does it means that all the free electrons of the metal are moving in the same direction ?

asked Jun 29, 2015 by meena.p

1 answer

If the electron drift speed is so small , and the electron's charge is small , how can we still obtain large amount of current in a conductor ?

asked Jun 29, 2015 by meena.p

1 answer

The electron drift arises due to the force experience by electrons in the electric field inside the conductor . But force should cause acceleration . When then do the electrons acquire a steady average drift speed ?

asked Jun 29, 2015 by meena.p

1 answer

The electron drift speed is estimated to be only a few $mms^{-1}$ for currents in the range of a few amperes. How then is current established almost instant a circuit is closed.

asked Jun 29, 2015 by meena.p

1 answer

Given n resistors each of resistance R, how will you combine them to get, (i) maximum effective resistance (ii) minimum effective resistance ? What is the ratio of the maximum to minimum resistance

asked Jun 29, 2015 by meena.p

1 answer

A high tension (HT) supply of say $6\;KV$ must have a very large internal resistance why ?

asked Jun 29, 2015 by meena.p

1 answer

Is Ohm's law universally applicable for all conducting element ? If not give example of elements which do not obey Ohm's law.

asked Jun 29, 2015 by meena.p

1 answer

A low voltage supply from which one needs high currents must have very low internal resistance why ?

asked Jun 29, 2015 by meena.p

1 answer

Careful measurement of the electric field at the surface of a black box indicate that net outward flux through the surface of the box is $8.0 \times 10^3 Nm^3 C^{-1}$ If the net outward flux through the surface that there were no changes inside the box. Why or why not ?

asked Apr 29, 2015 by meena.p

1 answer

Careful measurement of the electric field at the surface of a black box indicate that net outward flux through the surface of the box is $8.0 \times 10^3 Nm^3 C^{-1}$ What is the net charge inside the box ?

asked Apr 29, 2015 by meena.p

1 answer

Electric charge is distributed uniformly on the surface of a spherical rubber balloon. show how the value of electric intensity vary On outside the surface?

asked Apr 29, 2015 by meena.p

1 answer

Electric charge is distributed uniformly on the surface of a spherical rubber balloon. show how the value of electric intensity vary inside the surface ?

asked Apr 29, 2015 by meena.p

1 answer

Electric charge is distributed uniformly on the surface of a spherical rubber balloon. show how the value of electric intensity vary On the surface?

asked Apr 29, 2015 by meena.p

1 answer

When an electric dipole of moment $|P|=q \times 2a$ is held at an angle $\theta$ with the direction of uniform external field E, a torque $T= PE \sin \theta$ acts on the dipole. This torque tries to align the electric dipole in the direction of the field. When P is along E $\theta =0^{\circ} , t= PE \sin 0=zero$ An electric dipole of length 10 cm having a charge $\pm6 \times 10^{-3} \;C$ placed at $30^{\circ}$ with respect to a uniform electric field experiences a torque of magnitude $6 \sqrt 3 N-m$ . Calculate magnitude of electric field.

asked Apr 29, 2015 by meena.p

1 answer

When an electric dipole of moment $|P|=q \times 2a$ is held at an angle $\theta$ with the direction of uniform external field E, a torque $T= PE \sin \theta$ acts on the dipole. This torque tries to align the electric dipole in the direction of the field. When P is along E $\theta =0^{\circ} , t= PE \sin 0=zero$ What is the direction of torque acting on electric dipole held at an angle with uniform electric field?

asked Apr 29, 2015 by meena.p

1 answer

A paisa coin is made up of Al-my alloy and weights $0.75\;g$ It has a square shape and its diagonal measures $17\;mm$ It is electrically neutral and contains equal amounts of positive and negative charges. Treating the paisa coins made up only $Al$ , find the magnitude of equal number of positive and negative charges. What conclusion do you draw from this magnitude ?

asked Apr 29, 2015 by meena.p

1 answer

The dimensions of an atom of the order of an angstrom. Thus there must be large electric fields between the protons and electron . Why then is the electrostatic field inside a conductor zero?

asked Apr 29, 2015 by meena.p

1 answer

An arbitrary surface enclosed a dipole . what is the electric flux through this surface ?

asked Apr 29, 2015 by meena.p

1 answer

Suppose the particle in $Q_{33}$ is an electron projected with velocity $V_x =2.0 \times 10^6 m/s$ . If E between the plates separated by $0.5 \;cm$ is $9.1 \times 10^2 N/C$ , where will the electron strike the upper plate ? $(|e|=1.6 \times 10^{-19}\;C,m_e=9.1 \times 10^{-3}\;kg)$

asked Apr 29, 2015 by meena.p

1 answer

A particular of mass m and charge $(-q)$ enters the region between the two charged plates initially moving along x-axis with speed $V_x$ (like particle 1 in the figure) . The length of plate of L and a uniform electricity field E is maintained between the plates. she that the vertical deflection of the particle at the fan edge of the plate is 4qEl^2/2mv_x ^2$. Compare this motion with motion of a projectile in gravitational field.

asked Apr 29, 2015 by meena.p

1 answer

Verify this result for the simple configuration of two charge of the same magnitude and sign placed at a certain distance apart.

asked Apr 29, 2015 by meena.p

1 answer

Consider an arbitrary electrostatic field configuration . A small test charge is placed at a null point . ( i.e where $E=0$ )of the configuration . Show that the equilibrium of the test charge is necessarily unstable .

asked Apr 29, 2015 by meena.p

1 answer

It is believed that protons and neutrons (which constitute nucli of or ordinary matter) are themseleves built out of more elementary units called quarks. A proton and a neutron consists of there quarks each. Two type of quarks, the so called 'up' quark (denoted by u) of charge $+\bigg( \large\frac{2}{3}$ $e\bigg)$ and the down quark denoted by of charge $\bigg( \large\frac{-1}{3}$ $e\bigg)$ , together with electricity build up an ordinary matter. (quarks of other types have also been found which give rise to different ususual varieties of matter. ). Suggest a possible quark composition of a proton and neutron .

asked Apr 29, 2015 by meena.p

1 answer

A sensitive instrument is to shielded from the story electrostatic field in its environment . Suggest a possible way

asked Apr 28, 2015 by meena.p

1 answer

Another conductor B with charge q is inserted into the cavity keeping B insulted from A. Show that the total charge on the outside surface of A is $Q+q$ (fig b)

asked Apr 28, 2015 by meena.p

1 answer

In a certain region of space , electric field is along the z- direction throughout. The magnitude of electric field is, however not constant but increases uniformly along the positive z- direction, at the rate of $10^5 N/c-m$ . What are the force and torque experienced by a system having a total dipole moment equal to $10^{-7}c-m$ in the negative z- direction ?

asked Apr 28, 2015 by meena.p

1 answer

Ask Questions, Get Answers