Buzzing from light bar?

Not sure if this is good or not but I’m in the process of wiring my light bar and their is a buzzing going on when the light is on and connected to the relay!
If I connect the light bar directly to the switch with no relay the buzzing noise from the light is greatly reduced but can still be heard if you are listening for it.
So will this buzzing cause anything? Any issue? Premature wear?
Also what is the buzzing? Resistance from the terminals or something greater?
I know their are a few electrical gurus out their that may lend their .02$