A long solenoid with 10.0 turn $/ \mathrm{cm}$ and a radius of 8 cm carries a current of 7 mA . A current carrying straight conductor is located along the central axis of the solenoid. If the direction of resulting magnetic field is $60^{\circ}$ to axial direction at a point 5 cm from the axis of the solenoid along the radial direction, then the current in the conductor is [take, $\sqrt{2}=1.4, \sqrt{3}=1.7$ ]

A horizontal wire carries 160 A current below which another wire of linear density $10 \mathrm{~g} / \mathrm{m}$ carrying a current is kept at 4 cm distance. If the wire kept below hangs in air, what is the current in this wire, when the direction of current in both the wires is same? $\left(g=10 \mathrm{~m} / \mathrm{s}^2\right.$ and $\left.\mu_0=4 \pi \times 10^{-7}\right)$

A long solenoid has 70 turns / cm and carries current $I$. An electron moves within the solenoid in a circle of radius 2.5 cm perpendicular to the solenoid axis. If the speed of the electron is $4.4 \times 10^6 \mathrm{~m} / \mathrm{s}$, then the current $I$ in the solenoid is

(take $\mu_0=4 \pi \times 10^{-7}$ Si unit, mass electron $=9 \times 10^{-31}$

kg , charge of electron $1.6 \times 10^{-19} \mathrm{C}$ )

A current $I=5 \mathrm{~A}$ flows along a thin wire shaped as shown in figure. The radius of curved part of the wire is equal to $R=100 \mathrm{~mm}$, the angle $2 \phi=90^{\circ}$. The magnitude of magnetic field at the point $O$ is approximately

$$ \left(\text { use, } \frac{\mu_0}{4 \pi}=10^{-7} \mathrm{~T} \mathrm{~mA}^{-1}\right) $$