The carbon filament is invented by_____?

To hear a clear echo, the minimum distance should be______?

The centripetal force required for a car or a bicycle to go round a circular curve depends on___?

The lines of force of a uniform magnetic field____?

A cyclotron can accelerate___?

Principal focus of a spherical mirror is between____?

Who was the inventor of positron?

Who invented air conditioning?

The image form by an object of a compound microscope is ?

Richter scale is used for measuring___?

The size of the atomic nucleus is in the order of__?