Physics
Suitable impurities are added to a semiconductor depending on its use. This is done in order to

increase its life
increase its electrical resistivity
increase its electrical conductivity
enable it to withstand higher voltages

ANSWER DOWNLOAD EXAMIANS APP

Physics
Railway tracks are banked on curves

necessary centrifugal force may be obtained from the horizontal component weight of the train
to avoid frictional force between the tracks and wheels
the train may not fly off in the opposite direction
necessary centripetal force may be obtained from the horizontal component of the weight of the train

ANSWER DOWNLOAD EXAMIANS APP