According to the periodic table carbon lies in the list of
semiconductor having valency of 4 thus semiconductors have
the property that with increase in temp. their resistance
decreases. Thus when carbon brushes rub against the commutator
due to friction their temp. increases and resistance falls.
Thus they are used for collection of current in DC machines.
In AC systems slip rings are used.
A 2D array X(7,9) is stored linearly column wise in a
computers memory.Each element requires 4 bytes for the
storage of the value.If the first byte address of X(1,1) is
3000,what could be the last byte adress of X(5,8)?