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Draw a diagram to show the basic structure of the bi-polar transistor - Leaving Cert Physics - Question (ii) - 2017
Question (ii)
Draw a diagram to show the basic structure of the bi-polar transistor. State the relationship between the three currents flowing in a transistor circuit. Draw the ... show full transcript
Worked Solution & Example Answer:Draw a diagram to show the basic structure of the bi-polar transistor - Leaving Cert Physics - Question (ii) - 2017
Step 1
Draw a diagram to show the basic structure of the bi-polar transistor.
Answer
The basic structure of a bipolar transistor consists of three layers of semiconductor materials, either P-N-P or N-P-N configuration. In a P-N-P transistor, the emitter (E) is the P-type layer, the base (B) is the N-type layer, and the collector (C) is again a P-type layer. The connections are as follows:
- Emitter (E) is connected to the positive voltage (for P-N-P type).
- Base (B) is the control layer.
- Collector (C) is connected to the output.
A diagram representing this structure can be sketched with the following labels:
- An arrow indicating the direction of conventional current flow (from E to C).
- Referring to the connections as
n(N-type) andp(P-type).
Step 2
State the relationship between the three currents flowing in a transistor circuit.
Answer
In a bipolar transistor, there are three primary currents:
- (Emitter Current)
- (Base Current)
- (Collector Current)
The relationship between these currents is defined by the equation: This states that the emitter current is equal to the sum of the base current and collector current, highlighting how the base current controls the larger collector current.
Step 3
Draw the circuit diagram for a transistor circuit that can be used as a voltage inverter (NOT gate).
Answer
The circuit diagram for a voltage inverter (NOT gate) using a bipolar transistor is as follows:
- The collector of the transistor is connected to the positive voltage supply.
- The emitter is connected to the ground (earth).
- A resistor is connected in series with the base to limit the current. The input signal is applied to the base via this resistor.
This circuit configuration will output the inverted signal at the collector.