When an ignition coil goes bad the car will not run right, or not at all. An intermittent coil will cause shudder, or a jerking motion. When the coil has no output then the cylinder that the coil feeds cant burn the fuel and cause power.
The ignition coil is located just to the right of your car's engine. An easy way to locate it is to follow the wires from your spark plugs. The other end of the cable is connected to the ignition coil.