If the potential difference across a load is 60 volts and the resistance of the load is 10 ohms the current is amperes.?

It's not that simple.

The basic formula is Volts / Ohms = Amps.

For 30 Volts you'd get 0.5 Amps, for 60 Volts you'd get 1 Amp, for 120 Volts you'd get 2 Amps.