IGCSE/GCSE/O & A Level/IB/University Student Forum

Qualification => Subject Doubts => IGCSE/ GCSE => Sciences => Topic started by: gaurav95 on May 13, 2010, 06:38:19 am

Title: Physics
Post by: gaurav95 on May 13, 2010, 06:38:19 am

Can somebody solve the q 10
from both the papers.............The whole question  :) :) :) :)
I dont understand the m.s. also.......

Thanks in advance.......

Title: Re: Physics
Post by: Vin on May 13, 2010, 06:48:45 am

post ur question here from now on ..

https://studentforums.biz/index.php/topic,6468.780.html

wait a min lemme see the q.

Title: Re: Physics
Post by: Vin on May 13, 2010, 06:56:46 am

june 07
You should kno what is a thermistor .. a semi-conducting material which when temperature increases its resistance decreases .. resulting a fall in the p.d across R1 tht is the base emitter pd increases .. when it exceeds a certain amount the light is switched on ..

Title: Re: Physics
Post by: gaurav95 on May 13, 2010, 07:02:32 am

Quote from: ~VIN1094~ on May 13, 2010, 06:56:46 am

june 07
You should kno what is a thermistor .. a semi-conducting material which when temperature increases its resistance decreases .. resulting a fall in the p.d across R1 tht is the base emitter pd increases .. when it exceeds a certain amount the light is switched on ..

The 2nd q

Title: Re: Physics
Post by: Vin on May 13, 2010, 07:08:39 am

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 .. =|

Title: Re: Physics
Post by: gaurav95 on May 13, 2010, 08:26:19 am

Thanks  alot