VITEEE 2009 Paper

Here current flows in circuit A as both (p-n) junction diode act as forward biasing.
Total resistance R.

1

R

=

1

4

+

1

4

=

2

4

or R = 2Ω
According to Ohm's law
V=IAR‌‌‌or‌‌‌‌8=IA×2‌‌or‌‌IA=4A
In circuit B, lower p-n junction diode is reverse biased. Hence, no current will flow but upper diode is forward biased so current can flow through it . V=IBR‌‌‌or‌‌‌‌8=IB×4‌‌or‌‌IB=2A