Question

The number of scans of the complete 8-digit display that can be carried out in one second is

(a) 15

(b) 25

(c) 35

(d) 55

The question was posed to me by my college professor while I was bunking the class.

My question is from Interfacing With 8051 Ports -2 topic in portion Microcontroller 8051 of Microprocessor

Answer 1

Correct option is (b) 25

Easiest explanation: Starting from either right most or left most digit, every digit glows for 5 msec one by one. Thus one scan of the 8 digit display requires 40 msec. Thus in one second, 25 scans of the complete 8-digit display can be carried out.