nov 06
A - resistor
B -LDR or light dependent resistor
C - Transistor
D - Lamp
b) C
c) the lamp comes on when the LDR is in dark because more of battery pd being dropped across increased resistance (of LDR) which is greater than 0.6 V and less at A .. hence the base emitter pd increases as the base current and collector current
for these type of ques u need to kno the concept of potential divider very well .. sry to reply so late my nets bad .. =|