Figure 204 O 8020 sVe accelerator grid A mass spectrograph i

Figure 20.4 O 8-020 sVe accelerator grid A mass spectrograph is operated with deuterons, which have a dargr o., and a mans of 334·irgig bestenes emerge from the sounce, which is grounded with negligible velocity. The velocity of the deuterons as they pass through the accelerator grid is 8.0-105 ms A uniform magnetic field of magnitude B-020T.died out of the plane, is present at the right of the grid 9)In Figure 20 4, the deutenons are in circular orbit in the magretic field. The radius of the orbit and the initial sense of deflection are closest to A) 80 mm, downward B) 70 mm, downward C) 60 mm, downward D) 70 mn, upward E) 60 mm, upward Charge of (+) electron is 1.6× 10-19c Here Centripetal Force = magnetic force mv -mu-(3.34×10-27kg)(8.0 105m/s) (1.6x10-19C) (0.2T) (2.672x10-21) r= (3.2×10-20) r 0.0835m (0.0835m)(103mm) = 83.5mm 1m Hence 80mm downward

Solution

Yeah you are absolutely correct. Take the coordinate system: +ve x-axis toward right, +ve y-axis upwards, so +ve z-axis is coming out of the paper. Now vector v0=v0 xhat, B=B zhat(hat denotes unit vector). So take cross product v cross B, which is along (-yhat), i.e. downwards.

-Avijit Das(IST-4:30pm, 9/3/16)