Semiconductor Electronics : Materials Devices and Simple Circuits — Physics STD 12 Science — Question

The ratio of amplitude of a magnetic field to the amplitude of electric field for an electromagnetic wave propagating in vacuum is equal to:

Assertion : All the radioactive elements are ultimately converted in lead.
Reason     : All the elements above lead are unstable. (a) If both assertion and reason are true and the reason is the correct explanation of the assertion.(b) If both assertion and reason are true but reason is not the correct explanation of the assertion.(c) If assertion is true but reason is false.(d) If the assertion and reason both are false.

In the equation AB = C, A is the current density, C is the electric field, Then B is:

A P-type semiconductor can be obtained by adding (a) Arsenic to pure silicon(b) Gallium to pure silicon(c) Antimony to pure germanium(d) Phosphorous to pure germanium

A frog can be levitated in a magnetic field produced by a current in a vertical solenoid placed below the frog. This is possible, because the body of the frog behaves as

The charge on electron was discovered by (a) J.J. Thomson(b) Neil Bohr(c) Millikan(d) Chadwick

Between the plates of a parallel plate capacitor a dielectric plate is introduced just to fill the space between the plates. The capacitor is charged and later disconnected from the battery. The dielectric plate is slowly drawn out of the capacitor parallel to the plates. The plot of the potential difference across the plates and the length of the dielectric plate drawn out is