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How transistor acts as a switch and amplifier?
By turning a small input current into a large output current, the transistor acts like an amplifier. But it also acts like a switch at the same time. When there is no current to the base, little or no current flows between the collector and the emitter. So the base current switches the whole transistor on and off.
When can a transistor be used as an amplifier?
When the transistor is biased to use as an amplifier, the input signals cause the emitter current to flow, which later contributes to the collector current. This current when flows through the load resistor, it results in a large voltage drop across. This shows that a transistor acts as an amplifier.
When can a transistor be used as a switch?
One of the most common uses for transistors in an electronic circuit is as simple switches. In short, a transistor conducts current across the collector-emitter path only when a voltage is applied to the base. When no base voltage is present, the switch is off. When base voltage is present, the switch is on.
In which mode transistor acts as a switch?
A transistor works in active region when worked as an Amplifier. When a transistor works as a Switch it works in Cutoff and Saturation Regions. In the Cutoff State both Emitter Base Junction and Collector Base junctions are reverse biased. But in saturation region both junctions are forward biased.
How does a transistor work as an amplifier?
A transistor either works as a switch or as an Amplifier. It takes a tiny electrical current at one end (an input current) when it acts as an amplifier, and generates a much greater electrical current (an output current) at the other.
Which is an example of a transistor as a switch?
When this transistor is in a state where it is non-conducting, it acts as a switch in its off state and when it is in its saturation state, it acts as a switch in its on the state. The functioning of LED is the most common example of a transistor as a switch.
What is the current gain of a transistor?
The ratio of collector current to base current is known as the current gain of the transistor. With the base current at zero, the collector current would be zero and the transistor said to be ‘cut-off’.
When does a transistor remain in its active state?
In the case of a Si-transistor, we note that as long as the input voltage is less than 0.6 V, the transistor remains in the cut off state and the current I is zero, and hence we can write, is greater than 0.6 V the transistor remains in its active state and the current I c is obtained in the output path.