An electric heater conducts 4A current when 60 V is applied across its terminals. What will be the current if the potential defference is 120 V ?

When potential difference is applied between the ends of conductor the electrons will flow through the conductor with a constant average velocity. A potential ‘V’ Is applied across a conductor of length l . Keeping the potential difference same, the length of the conductor is halved. How does the velocity of electrons change?