Final answer:
The cross-sectional area of a copper wire with a diameter of 1.4 mm carrying a current of 20A is calculated using the area formula for a circle, resulting in approximately 1.54 mm².
Step-by-step explanation:
The student has asked to determine the cross-sectional area of a copper wire which has a diameter of 1.4 mm and is carrying a current of 20A. To find the cross-sectional area of the wire, one can use the formula for the area of a circle, A = πr^2, where r is the radius of the wire. Since the diameter is given as 1.4 mm, the radius would be half of that, which is 0.7 mm.
To convert millimeters to meters (since standard SI units are used in physics calculations), we use the conversion 1 mm = 1×10^-3 m. Therefore, the radius in meters is 0.7 mm × 1×10^-3 m/mm = 0.0007 m. Plugging this into the area formula, we get A = π × (0.0007 m)².
After calculating, the cross-sectional area of the copper wire is approximately 1.54 mm².