Experiment on Switching Action of Transistor

AIM:

INVESTIGATING THE SWITCHING ACTION OF TRANSISTORS.

MATERIALS: Battery 9V, 2 resistors (470Ω, 10Ω, 2 switches S1 and S2, 2 LEDS, L1 AND L2, 1 transistor) PROVIDE A DIAGRAM OF THE CONNECTION

METHOD:

i. Connect the circuit as shown above

ii. Open switch 1 and close with 2.

iii. Observe what happens to the LED in the collector – emitter section of the circuit.

iv. Close switch 1 and observe what happens to the two LEDS

OBSERVATION

When switch 1 was opened and switch2 was closed, the two LEDS in the collector – emitter section of the circuit did not light up. When both switch 1 and switch 2 were closed, the two LEDS lit up.

Closing the switch, a small current flowed through the base and drove the transistor into saturation region (this is when both the base-emitter and collector-base junctions are forward biased the transistor operates in saturation).

But when switch 1 was opened, there was no current to the base so the LEDS were off.