An unknown transistor needs to be identified as a $n-p-n$ or $p-n-p$ type. A multimeter, with +ve and -ve terminals, is used to measure resistance between different terminals of transistor. If terminal 2 is the base of the transistor then which of the following is correct for a $p-n-p$ transistor?

• A

  + ve terminal 2 , -ve terminal 3 , resistance low
• Correct answer
  B

  +ve terminal 2 , -ve terminal 1 , resistance high
• C

  +ve terminal $1,-$ ve terminal 2 , resistance high
• D

  +ve terminal $3,-$ ve terminal 2 , resistance high

Solution

$p-n-p$ transistor :
Positive at terminal 2 and negative at terminal 1 implies $p-n$ junction is reverse biased and hence offers high resistance.

Hence, the correct answer is option: 'B'.