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

Write an example in which the first law of thermodynamic is allowed but never be observed.

Which two physical quantities remains constant in law of conservation of momentum? Which quantity remain zero?

Draw the x to t graphs which represent the positive, negative and zero velocity

To find the direction of the magnetic field produced by a current -carrying wire, a magnetic needle is placed at different positions as shown in the following figure . Which position of the magnetic needle corresponds to the correct direction of the magnetic field ?

Which among average speed and average velocity can be positive, negative or zero ?

Depending on in which quadrant an angle theta lies, functions costheta and sintheta may be positive or negative. In the second column of the given lable are specified whether these functions are positive or negative and in the first column are specified quadrants. {:("Column-I","Column-II"),((A)" First",(P)sintheta" is positive"),((B)" Second",(Q)sintheta" is negative"),((C)" Third",(R)costheta" is negative"),((D)" Fourth",(S)tantheta" and "sintheta"both are negative"),(,(T)sectheta" is negative and "sintheta" is positive"):}

The following equations represent transverse waves : z_(1) = A cos(kx - omegat) , z_(2) = A cos (kx + omegat) , z_(3) = A cos (ky - omegat) Identify the combination (s) of the waves which will produce (i) standing wave(s), (ii) a wave travelling in the direction making an angle of 45^(@) with the positive x and positive y axes. In each case, find the positions at which the resultant is always zero.

(a) Magnetic field lines show the direction (at every point) along which a small magnetised needle aligns at the point). Do the magnetic field lines also represent the lines of force on 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's law of magnetism be modified? (d) Does a bar magnet exert a torque on itsell due to its own field? Does one element of a current-carrying wire exert a force on another element of the same wtre? (e) Magnetic field arises due to charges in motion. Can a system have magnetic moments even though its net charge is zero?