The electron beam in a cathode ray tube (TV or computer monitor) scans from the

Question

The electron beam in a cathode ray tube (TV or computer monitor) scans from the left to the right a horizontal line along the screen. When the scan of line is completed the beam is lowered to scan another line. After the most bottom line is scanned, the beam is brought back to the top line. In the US, which accepted the National Television Standards code system, there are 525 horizontal lines on TV which are scanned 30 times a second.Determine the direction of the magnectic fields which control both the horizontal and the vertical deflection of the electron beam.

Explanation / Answer

if the resultant force on electron due to electric field and magnetic field is zero then there is no deflection of the electron bem             So force on electron due to electric field = force on electron due to magnetic field                     E q = B q v sin?           if sin ?   = 1                  F_B   = F_ E              so the angle between magnetic field and electric field is 90 degrees      the horizontal and vertical deflectio of the eletron beam is controled when the direction of magnetic field is perpendicular to the electric field

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