What is the function of soft iron cylinder between the poles?

What is the unit of pole strength ?

A circular cylinder has an inextensible string wrapped around it as shown in the figure. What is the linear acceleration of the cylinder when released?

A rope of negligible mass is wound round a hollow cylinder of mass 3 kg and radius 40 cm. What is the angular acceleration of the cylinder if the rope is pulled with a force of 30 N ? What is the linear acceleration of the rope ? Assume that there is no slipping.

What is the colour of rust coating on iron?

A long charged cylinder of linear charged density lambda is surrounded by a hollow co-axial conducting cylinder. What is the electric field in the space between the two cylinders?

With the help of diagram explain the principle, construction and theory of a moving coil galvanometer. What is the function of iron core in moving coil galvanometer?

What is the condition for rolling of a solid cylinder withuot slipping on an inclined plane?

What is corrosion of iron called?