K.C.S.E Physics Q & A - MODEL 2005PP2QN04

K.C.S.E Physics Q & A - MODEL 2005PP2QN04

​Explain how doping producers an n-type semi-conductor for a pure semi-conductor material. 
b) Fig 5. Shows the circuit of a rectifier using four diodes D1, D2, D3 and d4.

(i) Explain how a rectified output is produced from the set – up when an a.c input is connected across AB 
(ii) On the axis provided sketch the graph of output voltage against time for rectifier 
(iii) A capacitor is now connected across XY. Explain the effect of the capacity on the output. 
(c) A transistor in a common-emitter amplifier has life = 120. A signal in the input causes the base corresponding change in the output voltage if the load resistance is 100n. 

answers