In soldering, addition of flux makes soldering easy. Why?

What is use of solder?

State whether the following statements are true or false: Solder is an alloy of copper and tin.

A rectangular coil carrying current is placed in a uniform magnetic field in such a way that normal to the coil makes an angle theta with the direction of magnetic flux density. Find the magnitude of torque acting on the coil Define magnetic moment of a current loop.

In which of the following situations,does the list of numbers involved make an arithmetic progression,and why?(i) The taxi fare after each km when the fare is Rs 15 for the first km and Rs 8 for each additional km.

Why should the material used for making permanent magnet have high coercivity?

In which of the following situations,does the list of numbers involved make an arithmetic progression,and why?(ii)The amount of air present in a cylinder when a vacuum pump remove 1/4 of the air remaining in the cylinder at a time .

Explain why friction is necessary to make the disc in Fig. 7.41 roll in the direction indicated. (a) Give the direction of frictional force at B, and the sense of frictional torque, before perfect rolling begins. (b) What is the force of friction after perfect rolling begins?