Answer / bala

A.C current having a sinusoidal wave form...D.C current having a straight live wave form.....in A.C power having a power factor....in D.C circuit not having a power factor...

Answer / amit kumar singh

The major differences in AC and DC are as follows:
1)The magnitude of DC does not change as long as load and
source voltage remain same and its mgnitude depends only on
resistance of load. But, in AC it varies as a function of
cosine and its magnitude depends on Impedence (R+jX) of the
load.
2)DC flows in only one direction in a circuit, but AC
changes its direction every half cycle.
3)Due to variable magnitde and direction of AC (oscillating
nature), it has a frequency of oscillation. But, DC has no
frequency (i.e. f=0).
4)AC has Skin Effect (i.e., it flows more at the surface of
conductor and lesser inside the conductor which is the
effect due to its frequency). But, as DC has zero
frequency, it flows throughout the volume of the conductor.

please send me previose rrb junior engineer qustion papers

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