Consider the velocity selector presented in lecture Let h be

Consider the velocity selector presented in lecture: Let h be the distance between the disks, theta is the angle of the slits from each other and v represent the rotational frequency in rotations/s. Let us say that the disks are 1.5 cm apart and angle between the slits is 2.5 degree. If the disk system is rotating at 350 rotations/second, what is the velocity of particles that will pass through the slit system?

Solution

So since the each of the disks are separated by 1.5 cm,only the particles having speed such that it can traverse this 1.5 cm by the time the next disc rotates by 2.5 degrees (it will then come in alignment with the previous disc\'s initial position). All the other velocities are blocked.

rotation speed = 350 rotations/sec

= 350*360 degrees/sec

=126000 degrees/sec

This implies, time taken for 1 degree rotation is 1/126000 =7.94 micro seconds.

Therefore time taken for 2.5 degrees=2.5*7.94 = 19.85 microseconds

So velocity of particles that can pass through all the discs=1.5cm/(19.85 microseconds)=75566.7 cm/s

= 7.56x10^(4) cm/s

=756m/s

%Hopefully my calculations are correct%