noticed today that my cars lights tend to dimm when i apply the brake, as i am sitting at a light lights dim car shakes a lil and sometimes the radio shuts off and then comes back on. battery is almost new i have the right cold cranking amps and alternator is fine. what else can cause this problem?

Check your ground from the engine to the car body.

Check your ground from the engine to the car body.

will have to chech that out tomorrow anything else that may cause this?

Altenator maybe, but if the car shakes as the light dims, then it sounds like the idle's too low. A low idle when the brakes are applied could indicate a faulty brake booster so that when the plunger is depressed it creates a vacuum leak. Use a vacuum testor to see if the brake booster holds vacuum when the brakes are at rest, and engaged.