Q. A working transistor with its three legs marked P, Q and R is tested using a multimeter. No conduction is found between P and Q. By connecting the common (negative) terminal of the multimeter to R and the other (positive) terminal to P or Q, some resistance is seen on the multimeter. Which of the following is true for the transistor?
A) It is an n-p-n transistor with R as base
B) It is an p-n-p transistor with R as collector
C) It is an p-n-p transistor with R as emitter
D) It is an n-p-n transistor with R as collector
Explanation
(a) Since no conduction is found when multimeter is connected across P and Q it means either both P and Q are $n$-type or $p$-type. So, it means $R$ is base. When $R$ is connected to common terminal and conduction is seen when other terminal is connected to P and Q, so it means transistor is in p-n with $R$ as base.
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.