Answer:
The magnetic field is doubled.
Step-by-step explanation:
What happens to the strength of the magnetic field if one more 1.5 v dry cell is added?
The magnetic field due to a current carrying conductor is directly proportional to the current flowing in the wire.
If we connect one more battery of 1.5 V so the voltage is doubled and according to the Ohm's law, as the resistance of wire is constant, so the current in the wire is also doubled.
When the current doubles, the magnetic field produced by the wire is also doubled.