Which one of the following scientists mentioned that an electron in an atom could revolve in certain stable orbits without the emission of radiant energy?

LIGO experiment confirmed one of the predictions of :

A block of mass 2 kg, moving with the initial speed of 3 m/s comes to rest on a rough horizontal surface after travelling a distance of 3 m. The magnitude of the frictional force is :

Which one of the following is primarily responsible for conduction of current in a metal?