The detection range on most sensors includes up to a 240 degree field of view, and a distance range of 70 feet or more. On some lights, the distance range can be adjusted through a setting on the light, while on other lights, you can adjust the detector either up (to increase range) or down (to lower range) to change the detection distance. Also, keep in mind that the motion detector will pick up any moving object that is giving off heat, including a passing car, your neighbor, an approaching person, a pet, blowing leaves, etc. As a result, you may experience undesired light triggering. However, most nuisance triggering can be avoided by properly and carefully setting the detection area through range settings and detector adjustment. A useful tip to fine tune your detection adjustments is to use black electrical tape to cover portions of the detector unit in order to block certain areas of the sensor. Trial and error will be needed to get the settings and range just right for your situation.
Most outdoor motion lights will also let you override the motion sensor, and use the light as a conventional switched light. In order to enter this override mode on most motion lights, flip the wall switch connected to the light off for a second, and then flip the switch back on. This should allow you to use your light in the dark as a switched light, leaving the light on even when no motion is detected. Flipping the light off, and then back on again, will usually allow you to exit this override state, and turn the motion sensor back on. Also, most lights will reset to motion-sensing operation when the photocell on the light detects daylight, causing the light to go into motion sensing operation the next evening. Make sure to consult the specific instructions for your light to enter override mode, if this feature is present.
You may be surprised at the features your motion light has--make sure to read the instructions to get the most out of your light!