State whether the following statement is true or false.
The magnetic field of an infinitely long ideal solenoid of radius $R$ carrying current $I$ is constant inside and zero outside.

Two identical long solenoids $X \text{and} Y$ carry equal current. The magnetic field produced at their axial mid-point is $B$. If both the solenoids are joined to each other according to figure, find magnetic field at axial mid-point of new solenoid.

Three identical long solenoids $P\text{,} Q \text{and} R$ are connected to each other as shown in figure. If the magnetic field at the centre of $P$ is $2.0 \mathrm{T}$, what would be the field at the centre of $Q$?

A charge ${10}^{–11} \mathrm{Cb}$ and $10^{–7} \mathrm{kg}$ mass moves with a velocity of ${10}^8 \mathrm{m} {\sec }^{-1}$ along $x$-axis. A uniform static magnetic field $0.5 \mathrm{T}$ is acting along the $y-$axis. The magnetic force (magnitude and direction) on charge is,

 A $2 \mathrm{MeV}$ proton is moving perpendicular to a uniform magnetic field of $2.5 \mathrm{T}$. The magnetic force on proton is,

An electron is moving at ${10}^6 \mathrm{m} {\sec }^{-1}$ in a direction parallel to a current of $5 \mathrm{A}$ flowing through an infinite long straight wire separated by a perpendicular distance of $10 \mathrm{cm}$ in air. The magnetic force experienced by the electron is,