QUESTIONS $(50$ Marks $)$

Briefly explain the contributions of Dr$.$ S$.$ William Shockley, Walter H$.$ Brattain, and John Bardeen to the development of the transistor.

$[8$ marks$]$

List four advantages of semiconductor devices over vacuum tubes.

$[4$ marks$]$

Using the network of Figure $1,$ if $R_L=470,$ determine

i$.,V_L$

$[3$ marks$]$

ii$.,I_L$

$[3$ marks$]$

iii. $I_Z$

$[3$ marks$]$

iv$.I_R$

$[3$ marks$]$

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

$[3$ marks$]$

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