Solve problems involving the magnitude and direction of magnetic fields around a straight electric current-carrying wire and inside a solenoid using 𝐵 = 𝜇𝑜 𝐼 2𝜋𝑟 and 𝐵 = 𝜇𝑜 𝑛𝐼.

A long straight wire carries a current of 18.0 A vertically upward. A solenoid with 2,500 turns and a length of 0.65 m is positioned with its axis parallel to the wire. The solenoid carries a current of 3.2 A and its centre is located 0.12 m from the wire. Determine the ratio of the magnetic field strength at the centre of the solenoid (due to the solenoid itself) to the magnetic field strength at the same point due to the straight wire. Show your working.

A long straight wire carries a current of 12 A. Calculate the magnetic field strength at a point 0.080 m from the wire. Show your working.

A research team is investigating the magnetic field inside different solenoid configurations. Table 1 shows data collected for three solenoids with varying specifications. Determine the current required in Solenoid C to produce a magnetic field strength equal to that of Solenoid A. Show your working.

A long straight wire carries a current of 4.0 A. The magnetic field strength is measured at a perpendicular distance of 0.050 m from the wire. Which single change would produce the greatest increase in the magnetic field strength at the measurement point?