Magnetic Field due to Current — Prelims Questions

An infinitely long straight conductor carries a current of $5,\text{A}$. What is the magnetic field strength at a point $2,\text{cm}$ away from the conductor? (Given: $mu_0 = 4pi \times 10^{-7},\text{T}cdot\text{m/A}$)

A circular coil of radius $R$ has $N$ turns and carries a current $I$. The magnetic field at its center is $B_0$. If the current is doubled and the number of turns is halved, what will be the new magnetic field at the center?

A long solenoid has 1000 turns per meter and carries a current of $2,\text{A}$. What is the magnetic field inside the solenoid? (Given: $mu_0 = 4pi \times 10^{-7},\text{T}cdot\text{m/A}$)

Two parallel wires, P and Q, are placed $10,\text{cm}$ apart. Wire P carries a current of $5,\text{A}$ into the page, and wire Q carries a current of $10,\text{A}$ out of the page. What is the direction of the magnetic field at a point midway between the wires?

Which of the following statements about Ampere's Circuital Law is INCORRECT?

A current $I$ flows along a long straight wire. A rectangular loop is placed near the wire as shown. If the loop is moved away from the wire with a constant velocity, what happens to the magnetic flux through the loop?