http://tinyurl.com/ybvwgmnw
Should I put some resistors between +5v and Vc? I just want to amplify currents to let LED works because I don't know the value of resistor between +5v and Vb if it's too high the LED won't work at all so I put the transistor to make sure it still work in that case.

 

The LED only needs a resistor and a voltage source. The transistor only adds un-needed components. Trust me.

 

Image in question (edited):


If this is homework, what is the purpose of the problem?

 

Depends on what you are trying to do.
If you want the LED to just stay on, use a resistor and LED alone. Omit the transistor as Dick says.

 

http://tinyurl.com/y7pkf7gd
Okay, I should give you more information about my school project.
I actually designed my own measurement water level and the problem is the water isn't a good conductor at all and its conductivity isn't constant depends on where I took the water from. So when I put it in the water my LED won't work at all. I decide to use transistors to amplify currents to make sure it still works when the conductivity of water is too low. I want to know is that okay to bias a transistor like I posted on the top because
the current from Emitter is the highest and I want to use it for my LED but I never saw someone bias a transistor like that before.

 

Yes, not a problem.

 

Appriciate, thanks a lot!