The neutral temperature of a thermocouple is $350\,^{\circ}C$ when the cold junction is at $0\,^{\circ}C$. When the cold junction is immersed in a bath of $30\,^{\circ}C$,the inversion temperature is .............. $^{\circ}C$.

In order to make the parabolas formed by singly ionized ions in one spectrograph and doubly ionized ions in another Thomson's mass spectrograph coincide,the electric fields and magnetic fields are kept in the ratios $1 : 2$ and $3 : 2$ respectively. Then the ratio of the masses of the ions is

Two straight long conductors $AOB$ and $COD$ are perpendicular to each other and carry currents $i_1$ and $i_2$. The magnitude of the magnetic induction at a point $P$ at a distance $a$ from the point $O$ in a direction perpendicular to the plane $ACBD$ is

$A$ particle of charge $+q$ and mass $m$ moving under the influence of a uniform electric field $E\hat i$ and a uniform magnetic field $B\hat k$ follows a trajectory from $P$ to $Q$ as shown in the figure. The velocities at $P$ and $Q$ are $v\hat i$ and $-2v\hat j$ respectively. Which of the following statement$(s)$ is/are correct?

Statement $(I)$: $A$ uniform electric field and a uniform magnetic field are pointed in the same direction. If an electron is projected in the same direction,the electron velocity will decrease in magnitude.
Statement $(II)$: Two infinitely long parallel wires are carrying current in the same direction. The magnetic field at a point midway between the wires is zero.
Statement $(III)$: No net force acts on a rectangular coil carrying a steady current when suspended in a uniform magnetic field.
Which of the following is correct?

Which of the following is not a unit of magnetic induction?