Why is base current smaller than emitter current?

Why is base current smaller than emitter current?

The base contains more holes than electrons. As the direction of current is opposite to the flow of electrons we can understand that current from the emitter is conducted to the base and the collector. Hence, the collector current will always be slightly less than the emitter current.

Why is the base current in a BJT is so much less than the collector current?

The base current in the BJT is due to the recombination of holes and electrons. If we take it the other way round, the larger the base current the greater is the recombination, so the collector current should reduce, but Beta Ic/Ib.

Why is base current small?

The base region is thin and lightly doped. Due to this, only a few of the large number of electrons emitted from heavily doped emitter recombined with holes in the base region, and hence base current is very low.

Why is base made thin than collector and emitter?

The base region in a transistor is made very thin so that there is a better conduction of majority carriers from emitter to collector through base. The base region in a transistor is doped lightly so that the number density of majority carriers (electrons in p-n and holes in n-p-n transistor) is low. …

Is collector current greater than base current?

The base current is 10 amps and the collector current is 1ma, so still the base current is much greater than the collector current.

How many times greater is the collector current then the base current?

For example, if the input current (IB) in a common emitter changes from 75 µA to 100 µA and the output current (IC) changes from 1.5 mA to 2.6 mA, the current gain (β) will be 44. This simply means that a change in base current produces a change in collector current which is 44 times as large.

Is the base region much thinner or much wider than the collector and emitter regions?

Transistors have three sections namely – the emitter, the base, and the collector. The base is much thinner than the emitter, and the collector is comparatively wider than both. The emitter is heavily doped so that it can inject large number of charge carriers for current conduction.

Which current is the smallest in BJT?

The base current IB is always the smallest. The collector current IC and emitter current IE are relatively close in magnitude. 7.

What is the difference between collector and emitter?

The main differences between emitter and collector are doping concentration and size. The emitter is heavily doped, while the collector is lightly doped. You could try to swap them, but you’ll get a very low HFE, probably even less than 1.

Why transistor is called current amplification device?

Transistor Amplifier A transistor acts as an amplifier by raising the strength of a weak signal. The DC bias voltage applied to the emitter base junction, makes it remain in forward biased condition. Thus a small input voltage results in a large output voltage, which shows that the transistor works as an amplifier.

Why is base width less?

The width of the region depends upon their doping. The base region is lightly doped so that width of the base is less. Collector region of a transistor is highly doped so collector region has more width than other two.

Why is base width small?

The width of the base region is kept very small so that most the injected charge carriers pass to the collector. A transistor is basically a Si on Ge crystal containing three separate regions.

Why is the collector current always less than the emitter current?

Collector current in a properly biased bipolar junction transistor is always slightly less than the emitter current in all modes, because the “missing” current is the base current. Why is the base current in a transistor so much less than the collector current?

What is the relationship between base current and collector current?

Smaller base current controls larger collector current, this is how amplification takes place. Small is relative term, current gain of the transistor decides how small base current would be than collector current. Most of the emitter current of electrons diffuses through the thin base into the collector.

Does the base current of a transistor have to be small?

It does not have to be . Small is a relative term. A transistor has current gain and so the base current would be much smaller than the collector and the load. The base current may be tens of amps, whihc is not small ,if the collector current was thousands of amps.

Why is the base current small in a BJT circuit?

In a BJT, the base current is small because the base region is small and the reverse biased collector junction voltage draws most of what are now minority carriers into the collector before they can exit the base.