Question

In a transistor, the emitter current is
(A) slightly more than the collector current
(B) slightly less than the collector current
(C) equal to the collector current
(D) equal to the base current

Answer 1

Hint :In a transistor, the conduction of current is due to both – holes and electrons. Holes are the sites with the deficiencies of electrons. In a transistor, the current is released by the emitter and received by the collector. Hence, by finding if the base absorbs current or releases it, we can find the relation between the emitter current and collector current.

Complete Step By Step Answer:
A transistor can be explained as a device made up of two PN junction diodes which can be arranged in two different positions namely NPN transistors and PNP transistors.
In a transistor, the region in the middle is known as the base. The region on one side of the base is the emitter and on the other side, it is the collector.
As the conduction of electricity in the diodes is due to the impurities, the value of current depends on the concentration of the impurities. Thus, the more is the concentration of impurities, the more will be the emission of current.
In the transistor, the impurity concentration of the emitter is the highest, and the resistivity is the lowest. The impurity concentration of the base is the lowest, and the resistivity is the highest. The impurity concentration of the collector is more than the base but less than the emitter.
For an NPN transistor, the junction of emitter and base is connected to the battery in forward bias while the junction of collector and base is connected to the battery in reverse bias.
Due to forward bias, the electrons jump from the emitter to the base. The base contains more holes than electrons. But as the volume of the base is small, it absorbs about $ 5\;% $ of the electrons, and the rest is transferred to the collector.
As the collector is reverse biased, for every electron that enters the collector, the battery removes one electron from the collector.
Hence, we can say that during the whole process, the electrons come out of the base and collector and enter the emitter.
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.
Hence, the correct answer is Option $ (B) $ .

Note :
We know that the concentration of the impurities in the collector is slightly less than the concentration in the emitter. Hence, even if you apply the battery at the junction of the collector and the base in forward bias, the emitter current will always be greater than the collector current.