This week's book giveaway is in the OCMJEA forum. We're giving away four copies of OCM Java EE 6 Enterprise Architect Exam Guide and have Paul Allen & Joseph Bambara on-line! See this thread for details.
The conversion from long to float is "widening" in terms of range -- not bit size.
A 32-bit float has a much greater range than a 64-bit long, but this is because the float gives up precision. This has to do with the way in which floating-point values are typically stored in computers.