In a Thomson mass spectrograph,the electric field and magnetic field are applied:

Select the dimensional formula of $\frac{B^2}{2\mu_0}$.

An electron moves straight inside a charged parallel plate capacitor of uniform charge density $\sigma$. The space between the plates is filled with a uniform magnetic field of intensity $B$,as shown in the figure. Neglecting the effect of gravity,the time taken for the straight-line motion of the electron in the capacitor is:

Match the following and find the correct pairs.

List-$I$	List-$II$
$(A)$ Fleming's left hand rule	$(i)$ Direction of induced current
$(B)$ Right hand thumb rule	(ii) Magnitude and direction of magnetic induction
$(C)$ Biot-Savart law	(iii) Direction of force due to magnetic induction
$(D)$ Fleming's right hand rule	(iv) Direction of magnetic lines due to current

The current flowing along the path $A B C D$ of a cube (shown in the left figure) produces a magnetic field at the centre of the cube of magnitude $B$. Dashed lines depict the non-conducting part of the cube. Consider a cubical shape shown to the right which is identical in size and shape to the left. If the same current now flows in along the path $D A E F G C D$,then the magnitude of the magnetic field at the centre will be

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