$A$ proton beam is moving from north to south and an electron beam is moving from south to north. Neglecting the Earth's magnetic field,the electron beam will be deflected (assuming zero gravity):

In the following hexagons,made up of two different materials $P$ and $Q$,current enters and leaves from points $X$ and $Y$ respectively. In which case is the magnetic field at its centre not zero?

$A$ current-carrying closed loop in the form of a right-angled isosceles triangle $ABC$ is placed in a uniform magnetic field acting along $AB.$ If the magnetic force on the arm $BC$ is $\vec F,$ the force on the arm $AC$ is

The temperature at which the thermo-electric power of a thermocouple becomes zero is called:

Choose the correct statement.

$A$ mass spectrometer is a device which selects particles of equal mass. An ion with electric charge $q > 0$ and mass $m$ starts at rest from a source $S$ and is accelerated through a potential difference $V$. It passes through a hole into a region of constant magnetic field $\vec B$ perpendicular to the plane of the paper as shown in the figure. The particle is deflected by the magnetic field and emerges through the bottom hole at a distance $d$ from the top hole. The mass of the particle is: