This principle is known as Doping. Adding of an impurity to a pure semi conductor in order to increase certain properties.
43) Suitable impurities are added to a semiconductor depending on its use. This is done in order to
increase its electrical conductivity
Related General Physics MCQ with Answers
the refractive index of the different layers of the earth's atmosphere changes continuously, consequently the position of the image of a start changes with time
The scientific name for the twinkling of stars is stellar scintillation (or astronomical scintillation). Stars twinkle when we see them from the Earth's surface because we are viewing them through thick layers of turbulent (moving) air in the Earth's atmosphere.
in the hills the atmospheric pressure is lower than that in the plains and therefore water boils at a temperature lower than 100oC causing an increase in cooking time
I would like to give you an example "Pressure Cooker". The pressure level inside the Cooker is increased to 15 PSI(Pounds per square inch). So the rise is cooked at the temperature 120 degree Celsius. Therefore, the rise is cooked in 15 minutes. If you cook the rise in an open vessel, it will take up to 30 minutes to cook the rise. Because the rise is cooked in 100 degree Celsius (because of the normal atmosphere which is less than that inside the Pressure cooker). That's why it takes much time to cook. Similarly, in the hills the atmospheric pressure is lower than that in the plains and therefore water boils at a temperature lower than 100 degree Celsius causing an increase in cooking time.
tensor
Inertia is an external force which create tension to the object in respect of gravity it can be in any direction.
mirage
It is an optical illusion in which atmospheric refraction by a layer of hot air distorts or inverts reflections of distant objects.