Question

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 npn transistor with R as collector
• B. It is a pnp transistor with R as emitter
• C. It is a pnp transistor with R as collector
• D. It is an npn transistor with R as base
  

Answer 1

The correct option is D

It is an npn transistor with R as base

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 negative terminal and conduction is seen when other terminal is connected to P or Q, it means transistor is npn with R as base.