$A$ straight conductor carries a current of $5 \, A$. An electron travelling with a speed of $5 \times 10^6 \, m/s$ parallel to the wire at a distance of $0.1 \, m$ from the conductor,experiences a force of:

Two long parallel wires carry currents $I_1$ and $I_2$ $(I_1 > I_2)$. When currents are flowing in the same direction,the magnetic field at a point midway between the wires is $6 \times 10^{-6} \ T$. If the direction of $I_2$ is reversed,the field at the midpoint becomes $3 \times 10^{-5} \ T$. The ratio $I_1 : I_2$ is

Two straight horizontal parallel wires are carrying the same current in the same direction, and $d$ is the distance between the wires. You are provided with a small freely suspended magnetic needle. At which of the following positions will the orientation of the needle be independent of the magnitude of the current in the wires?

Two long straight parallel wires are separated by a distance $2d$. Each wire carries a current $I$ in the same direction. The magnetic field at a point $P$ midway between them is

Two parallel wires situated at a distance $2a$ are carrying equal currents $i$ in opposite directions as shown in the figure. The value of the magnetic field at a point $P$ situated at equal distances $r$ from both the wires will be:

$A$ particle carrying a charge equal to $100$ times the charge on an electron is rotating one rotation per second in a circular path of radius $0.8 \ m$. The value of magnetic field produced at the centre will be $(\mu_0 = \text{permeability of vacuum})$