Explanation :
A power amplifier is used to amplify electric signals i.e. to increase the low power signal to higher powers.
A PNP transistor is connected in a circuit so that the collector-base junction remains reverse biased and the emitter-base junction is forward biased.
This transistor can be used as a power amplifier because it gives a much larger output current. The gain of an amplifier shows the amount of amplification. It is the difference between the input and the output signals.
Mars.
Water exists as small amounts of ice on Mars and as water vapor. It is suspected that Mars used to have flowing water on it, but that there is none left now.
the relatively thick part of the earth's crust that forms the large landmasses. It is generally older and more complex than the oceanic crust.
The first successful flyby of Venus was performed by NASA's Mariner 2 spacecraft on 14 December 1962, following failed attempts by both the Soviet Union and the USA. The first successful landing was the Soviet Venera 4 lander, which touched down on the surface on 18 October 1967