B$1.$ For the circuit shown in Figure B$1,$

$($a$)$ state with reason whether the diode is reverse biased or forward biased. Support your answer with calculations.

$[6$ marks$]$

$($b$)$ calculate the currents flowing through resistors R$1$ and R$2.$ Indicate the directions of both currents.

$[6$ marks$]$

$($c$)$ calculate the current flowing through the silicon diode.

$[2$ marks$]$

figure b$1$