JEE Main 2021 · PhysicsMultiple choiceSingle correctEasyRecall

JEE Main 18 March 2021, Shift 2, Physics Q15

Question 15 of 90 in this shift, Physics question 15 of 30, Section A.

The correct relation between

\alpha

(ratio of collector current to emitter current) and

\beta

(ratio of collector current to base current) of a transistor is :

(1) $\beta=\frac{\alpha}{1+\alpha}$
(2) $\alpha=\frac{\beta}{1-\alpha}$
(3) $\beta=\frac{1}{1-\alpha}$
(4) $\alpha=\frac{\beta}{1+\beta}$ Official answer

Official answer

Option 4

NTA final key.

Chapter: Semiconductor Electronics: Materials, Devices and Simple Circuits
Topic: Transistors
Idea tested: Current Gains Alpha and Beta

Same idea in other shifts

Asked 4× in all

12 Apr 2023, Shift 1 · Q49In an n-p-n common emitter (CE) transistor the collector current changes from 5 mA to 16 mA for the change in base current from 100 $\mu$ A…EasySingle correct
27 Aug 2021, Shift 2 · Q17For a transistor $\alpha$ and $\beta$ are given as $\alpha=\frac{I_C}{I_E}$ and $\beta=\frac{I_C}{I_B}$ . Then the correct relation between…EasySingle correct
24 Feb 2021, Shift 1 · Q16If an emitter current is changed by 4 mA, the collector current changes by 3.5 mA. The value of $\beta$ will be :EasySingle correct

Question text from the official JEE Main paper published by NTA; answer from the final answer key. Chapter, topic and idea tags, difficulty and skill are Lumi’s. Lumi analyses 108 of the 174 JEE Main shifts held from 2017 to 2026.