Why is phosphor-bronze used as the material of the suspension-thread in a suspended coil galvanometer?

Answer the following why is it necessary to introduce a cylindrical soft iron core inside the coil of a galvanometer ?

Why is red phosphorous used in the reaction between HI and CH_3 OH during the preparation of methane ?

Which material is used for the metre bridge wire and why ?

MgO is used as a refractory material- Explain why?

Which material is used for potentiometer wire and why?

Why only certain materials are used as ingredient of electrical fuse ?

If the torsional rigidity per unit angle of twist of the suspension of the coil is k, find out an expression for the current sensitivity of galvanometer.

The magnets of two suspended coil galvanometer are of the same strength so that they produce identical uniform magnetic fields in the region of the coils. The coil of the first one is in the shape of a square of side a and that of the second one is circular of radius (a)/(sqrtpi) . When the same current is passed throught the coils, the ratio of the torque experienced by the first coil to that rxperienced by the second one is

The magnets of two suspended coil galvanometers are of the same strength so that they produce identical magnetic fields in the region of the coils. The coil of the first one is in the shape of a square of side a and that of the second one is circular of radius a// sqrt(pi) . when the same current is passed through the coils, the ratio of the torque experinced by the first coil to the experinced by the second one is