Question

What is the role of the focus section in a CRO?

(a) increases the focus

(b) decreases the focus

(c) controls sharpness

(d) maintains the focus zero

I had been asked this question in my homework.

Enquiry is from Front Panel Controls of CRO topic in section Oscilloscopes of Electrical Measurements

Answer 1

Right answer is (c) controls sharpness

The best I can explain: In a Cathode Ray Oscilloscope the focus section controls the sharpness of the visible spot on the screen. By varying the voltage applied to the focussing anodes, visible spot on the screen is focussed sharply.