In a cathode ray oscillograph, the focusing of beam on the screen is achieved by

Options

A. convex lenses
B. magnetic field
C. electric potential
D. all of these

Answer

C

Explanation

In a cathode ray oscillograph, the focusing of beam on the screen is achieved by electric potential. There are two plates X and Y. X plates consists two plates `X_(1) and X_(2)` in vertical plane while Y plates also consist two plates `Y_(1) and Y_(2)` in a horizontal plane. An electric potential is applied between the X and Y plates by an external source.