QUESTION NO$.4(25$ Marks$)$

a$)$ Describe four advantages of semiconductor devices over vacuum tubes.

rigure $4$

b$)$ Using the network of Figure $4,$ if $R_L=470,$ determine

i$.,V_L$

$[2$ marks$]$

ii$.,I_L$

$[2$ marks$]$

iii. $I_Z$

$[2$ marks$]$

iv$.,I_R$

$[2$ marks$]$

c$)$ Using the network of Figure $4$ above, determine the value of $R_L$ that will establish maximum power conditions for the Zener diode.

d$)$ Using the network of Figure $4$ above, determine the minimum value of $R_L$ to ensure that the Zener diode is in the $"$on$"$ state.