Question

which resistor protects the
transistor due to excessive current ?
​

Answer 1

Answer:

a temperature dependent resistor TDR protects a transistor owing to excess current

Answer 2

Answer: base resistor

Explanation:

If the transistor is switching a load with a coil (such as a motor or relay) instead of an LED you must include a protection diode across the load. in the example below) to protect the transistor when the variable resistor is reduced to zero, otherwise excessive base current will destroy the transistor