Once you've got more than a few years' experience as an engineer, people generally expect you to start mentoring others. How should you approach this?
In the years I've spent mentoring other Engineers, I've noticed there are three ways to answer requests from others for help or advice:
a) Try to point people in the right direction, discuss the problem, talk around the question and help them solve it themselves. If neither of you know the answer, work together to solve the problem. That way, you both get to learn something.
b) Answer the question directly and let them figure out themselves why that's the answer.
c) Answer the question in a patronizing and passive-aggressive way, because they should really know this. If you can mix in some disappointment and/or disgust that they not only do not know the answer, but that they dared to bother YOU with the question, then that's worth extra! Even more if you make them feel so foolish that they warn their colleagues that it's not worth bothering you with questions!
Different types of people gravitate towards each method. Personally I tend to use (a). Even though you might think I've exaggerated (b), and especially (c), for effect, I've known people who really are like that. I'm assuming they don't realize the reason why people don't ask them many questions is because everyone thinks they're unapproachable, rude, or worse.
If you think helping, pairing with or mentoring other engineers is an optional part of your job, you're wrong. They're all part of the responsibilities of senior engineers - even more so if you're a PE, PEng, CEng or any other professionally registered engineer. We all know it pops up in our CPD record requests! It's also true that if you can't explain a concept to someone, you don't understand it enough yourself. Mentoring is a good way to find this out, and helps to uncover gaps in your own knowledge.
So next time someone asks for help, and you're able to, maybe you should give it a try. To quote a friend of mine: "You're a senior engineer. Act like one!"