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

  • Thread starter Thread starter Jason7fd
  • Start date Start date
  • Tags Tags
    Switch Transistor
AI Thread Summary
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
Messages
3
Reaction score
0

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


none


The Attempt at a Solution


none
 
Last edited by a moderator:
Physics news on Phys.org
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.
 

Thread 'Struggling to understand the concept of this question (ice cube in water optics question)'

TL;DR Summary: I came across this question from a Sri Lankan A-level textbook. Question - An ice cube with a length of 10 cm is immersed in water at 0 °C. An observer observes the ice cube from the water, and it seems to be 7.75 cm long. If the refractive index of water is 4/3, find the height of the ice cube immersed in the water. I could not understand how the apparent height of the ice cube in the water depends on the height of the ice cube immersed in the water. Does anyone have an...
View full post »
Thread 'Variable mass system : water sprayed into a moving container'

Thread 'Variable mass system : water sprayed into a moving container'

Starting with the mass considerations #m(t)# is mass of water #M_{c}# mass of container and #M(t)# mass of total system $$M(t) = M_{C} + m(t)$$ $$\Rightarrow \frac{dM(t)}{dt} = \frac{dm(t)}{dt}$$ $$P_i = Mv + u \, dm$$ $$P_f = (M + dm)(v + dv)$$ $$\Delta P = M \, dv + (v - u) \, dm$$ $$F = \frac{dP}{dt} = M \frac{dv}{dt} + (v - u) \frac{dm}{dt}$$ $$F = u \frac{dm}{dt} = \rho A u^2$$ from conservation of momentum , the cannon recoils with the same force which it applies. $$\quad \frac{dm}{dt}...
View full post »

Similar threads

Designing a +10V Supply with Transistors: A Practical Approach
Replies
1
Views
1K
Transistor acting as a switch in closed circuit (with a thermistor)
Replies
3
Views
3K
What Is the Current Amplification Ratio in a Bipolar Junction Transistor?
Replies
3
Views
2K
Simulation of transistor switch circuit
Replies
5
Views
3K
Calculate resistance if the switch is closed 2 battery with different voltage
Replies
6
Views
3K
NPN BJT transistor: base voltage / emitter current
2
Replies
60
Views
15K
BJT transistor analysis: common emitter confusion
Replies
5
Views
3K
Calculating the amplification of a transistor
Replies
5
Views
2K
Finding R, I & V in an PLC output interface
Replies
6
Views
3K
Transistor as an amplifier (doubt)
Replies
3
Views
1K

Hot Threads

Recent Insights

Back
Top