The value of
in a transistor circuit with a nominal collector current
of 10mA is 70 Ohms.
To determine the value of
(emitter resistor) in a transistor circuit with a nominal collector current
of 10mA, we can use Ohm's Law
.
The emitter current
is approximately equal to the sum of the collector current
and the base current
in a transistor circuit.
![\[ I_e = I_c + I_b \]](https://img.qammunity.org/2024/formulas/physics/high-school/vsl8sh1i0n5xqejg7pg8xu4kj9z12ptylt.png)
Assuming a small base current
, we can approximate
to be equal to
.
Given that
, we can now choose the emitter resistor
using Ohm's Law:
![\[ R_e = (V)/(I_e) \]](https://img.qammunity.org/2024/formulas/physics/high-school/66ueaci9bch2t3zsskvmwaf17rp1ze2aqq.png)
The voltage across the emitter resistor V is typically around 0.7V for a silicon transistor.
Let's calculate:
![\[ R_e = (0.7V)/(10mA) \]](https://img.qammunity.org/2024/formulas/physics/high-school/kivyxsudqd7j08u7ibtskoxqs31dmkmdv5.png)
= 70 Ohms