Electromagnetic Waves — Physics STD 12 Science — Question

Production of electricity from magnetism is called.

In a p-n junction:

The capacitance of an air capacitor is 15 μF the separation between the parallel plates is 6mm. A copper plate of 3mm  thickness is introduced symmetrically between the plates.  The capacitance now becomes(a) 5 μF (b) 7.5 μF (c) 22.5 μF (d) 30 μF

Assertion  :   A circular loop carrying current lies in XY plane with its center at origin having a magnetic flux in negative Z-axis.
Reason      : Magnetic flux direction is independent of the direction of current in the conductor.(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.

ECG is a method of diagnosis used to check the functioning of heart, it is based on the principle that there is:

A potentiometer can measure emf of a cell because:

Choose the correct answer from the alternatives given.
The amplitude of an electromagnetic wave in vaccum is doubled with no other changes made to the wave. As a result of this doubling of the amplitude, which of the following statement is correct?

Figure shows the ray diagram of a:

The percentage of Sun's total energy which reaches the earth's surface is