A transmitting antenna is kept on the surface of the earth. The minimum height of receiving antenna required to receive the signal in line of sight at $$4 \mathrm{~km}$$ distance from it is $$x \times 10^{-2} \mathrm{~m}$$. The value of $$x$$ is __________.

(Let, radius of earth $$\mathrm{R}=6400 \mathrm{~km}$$ )

Two identical heater filaments are connected first in parallel and then in series. At the same applied voltage, the ratio of heat produced in same time for parallel to series will be:

As per the given graph, choose the correct representation for curve $$\mathrm{A}$$ and curve B.

Where $$\mathrm{X}_{\mathrm{C}}=$$ reactance of pure capacitive circuit connected with A.C. source

$$\mathrm{X}_{\mathrm{L}}=$$ reactance of pure inductive circuit connected with $$\mathrm{A} . \mathrm{C}$$. source

R = impedance of pure resistive circuit connected with A.C. source.

$$\mathrm{Z}=$$ Impedance of the LCR series circuit $$\}$$

The current sensitivity of moving coil galvanometer is increased by $$25 \%$$. This increase is achieved only by changing in the number of turns of coils and area of cross section of the wire while keeping the resistance of galvanometer coil constant. The percentage change in the voltage sensitivity will be: