Apply the first law of thermodynamics to a resistor carrying a current `i`. Identify which of the quantities `DeltaQ`, ` Delta U and DeltaW` are zero, which are positive and which are negative.

Which is irrelevant to the first law of thermodynamics?

Consider a 10-cm long piece of a wire which carries a current of 10A . Find the magnitude of the magnetic field due to the piece at a point which makes an equilateral triangle with the ends of the piece.

A constant current I is maintained in a solenoid. Which of lthe following quantities will increase if an iron rod is inserted in the solenoid along its axis?

Which of the following quantities do not change when a resistor connected to a battery is heated due to the current?

a. Magnetic field lines show the direction (at every point) along which a small magnetised needle aligns (at the point) Do the magnetic field also represent the lines of force one a moving charged particle at every point ? b. Magnetic field lines can be entirely confined within the core of a toroid , but not within a straight solenoid. Why ? c. If magnetic monopoles existed, how would the Gauss ' law of magnetism be modified ? d. Does a bar magnet exert a torque on itself due to its own field ? Does one element of a current - carrying wire exert a force on another element of the same wire ? e.Magnetic field arises due to charges in motion . Can a system have magnetic moments eventhough its charge is zero ?

Consider a coaxial cable which consists of an inner wire of radius a surrounded by an outer shell of inner and outer radii b and c respectively. The inner wire carries an electric current (i_0) and the outer shell carries an equal current in opposite direction. Find the magnetic field at a distance x from the axis where b.

A regular polygon of n sides is formed by bending a wire of total length 2 pi r which carries a current i. (a) Find the magnetic field B at the centre of the polygon. (b) By letting n rarr oo , deduce the expression for the magnetic field at the centre of a circular current.

A tightly-wound, long solenoid has n turns per unit length, a radius r and carries a current i. A particle having charge q and mass m is projected from a point on the axis in a direction perpendicular to the axis. What can be the maximum speed for which the particle does not strike the solenoid?