In my opinion a 10 gallon is too small of a tank to use a light, because as mentioned before, you'll find it difficult to provide proper temperature gradient in such a small tank. Leopard geckos need a hot side that has 90-95 degrees of belly heat, and the cold side of room temperature in 70's and low 80's. If you shine a light into a 10 gallon, it's likely to heat up the whole tank.
A low wattage ceramic heat emitter will allow you to supplement heating if you really need to raise the hot side temperature. But please remember having an under tank heating pad is more important than basking light or the air temperature.