I know that relays are used for heating element or any electronic other device with high wattage/high current. But for my application, I am using a Nichrome wire as a heating element and only want to provide power of 100mW, for that I need a current of approximately 71mA current(which I already calculated). I will be using a microcontroller to control it and will be turning it on and off at regular intervals. I was planning to use BJTs as my current driver circuits but then someone suggested me about relays. The maximum current that the MCU pin can provide is 50mA. I could only find applications with high wattage that use relays for example in automotive applications. Can someone suggest me if using relays would work for my application? Or if they would work which I think they will, would it be better than using BJT as a current driving circuit?
A PWM transistor switch can regulate the average current, or you can choose a better uC such as a PIC12 that supports max. current out of low 200 mA or 150 mA high.
100mW @ 71mA = 1.4V or 20 Ohms choose duty cycle from 1.4/Vdd supply voltage ratio and add a flyback diode for wire inductance.
ZTX450 NPN. 200~300 Ohm base drive from 3V, PWM 40%.
My question has been answered in the comments which I am going to summarize here: As @mkeith and @KyleB have mentioned that relays won't provide any advantage unless there is a requirement of electrical isolation. Further as @ChrisStratton mentioned, it is harder to drive relays. A better solution would be to use MOSFETs/BJTs as most of the comments suggest and another way is to follow answer by @TonyStewartEE75.