Calculate Collector Current w/ Emitter @ 100mA - Transistor Switch

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The discussion revolves around calculating the collector current of an N-P-N transistor when the emitter current is 100mA, given a thermistor resistance of 120 ohms and a resistor R1 of 600 ohms. Participants highlight the need for additional information, such as the value of resistor R2 and clarification on the transistor's configuration, including which terminal is the emitter or collector. There is confusion regarding the operation of the bipolar junction transistor (BJT) in forward-active mode and the significance of the beta parameter. The lack of foundational knowledge about BJTs is noted as a barrier to solving the problem effectively. Overall, the conversation emphasizes the importance of complete information and understanding of transistor operation for accurate calculations.
Jason7fd
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Homework Statement


http://img300.imageshack.us/img300/2640/17569077cy5.jpg
The transistor is a N-P-N type. When the siren is functional, the resistance of thermistor is 120 ohm. R1 is 600 ohm. The question is "Calculate the collector current if the emitter current is 100mA". I know that current of emitter = current of collector + current of base, but how do I find the base current? Another one, "what is the maximum voltage across R1 if the siren is functional?".

Homework Equations


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The Attempt at a Solution


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You didn't provide the value of R2. Also you didn't specify which end of the BJT is the emitter or collector. Is the BJT functioning in forward-active mode?
 
Defennder said:
You didn't provide the value of R2. Also you didn't specify which end of the BJT is the emitter or collector. Is the BJT functioning in forward-active mode?
I hav updated the schematic diagram. Sorry, I am not sure what are BJT and forward-active mode. The value of R2 is not provided in this question.
 
Uh, how are you expected to do this question if you don't know how a bipolar junction transistor (BJT) works in circuits? Do you know the equation for collector current in terms of VBE? What is value of B, the beta parameter of the BJT?
 
Defennder said:
Uh, how are you expected to do this question if you don't know how a bipolar junction transistor (BJT) works in circuits? Do you know the equation for collector current in terms of VBE? What is value of B, the beta parameter of the BJT?
I wish I was taught about this in school but they are not in the syllabus. It is a question from O-level Physics of Malaysia.
 
Hi, could you post the question exactly as it is ? Because what you have provided so far is insufficient.
 
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