Two long wires and are made of the same metal but have different circular cross-sections

PHYSICS · Multi-part · AP · Physics 2: Algebra-based · Electric Circuits · Electric Circuits

Problem

Two long wires

P

and

Q

are made of the same metal but have different circular cross-sections. Wire

P

has cross-sectional area

1.2\,\text{mm}^2

while wire

Q

has area

0.30\,\text{mm}^2

. Each wire is required to carry a steady current of

2.0\,\text{A}

. (i) For each wire, calculate the current density. (ii) Determine the ratio of the drift velocities

v_{dQ}/v_{dP}

of the conduction electrons in the two wires. (iii) Comment on which wire will have the higher electric field under these conditions.