Since the iMac was released in 1998, Apple has provided a variety of methods for users wanting to present information on a television. Thankfully, technological advances since its original release make it much easier to mirror your iMac's display or use a television to extend its desktop. Determining your iMac model is crucial in learning which adaptors and cables you will need to complete the process. A convenient way of finding the specific model name is to enter the machine's serial number into Apple's support website at Apple.com.
Purchase the correct adaptor from an online retailer such as MacMall.com or Apple.com. You'll need the Apple VGA adaptor for iMac G4 models and early iMac G5 models (2004 to 2006). You can also use the Mini-DVI adaptor for early iMac G5s. For later iMac G5 models (mid-2007 to 2009), you'll need the Mini-DVI or Mini Display port adaptor.
Boot your iMac and connect the appropriate adaptor to the leftmost port on the computer's rear.
Turn the television on and connect the adaptor to the appropriate port. Your TV's manual will tell you where to connect the computer adaptor.
Toggle your television's video input to the selected adaptor. This is frequently available on remote control buttons such as "Input."
Open the "System Preferences Displays" tab on your iMac to control resolution and video-mirroring capabilities.
Original-form iMacs (sold 1998 to 2001) require a third-party external USB adaptor to route video to a television or projector. Apple's Apple VGA, Mini-DVI and Mini DisplayPort connectors have a short length, so female-to-male extension cable will help if you're dealing with longer distances. To play iMac audio through your television, attach a male-male minijack cable from the iMac to your television. No further configuration is required.