Measurements

Explanation of question 30

A frequency meter has a quoted tolerance of 10 parts per 100,000. When measuring a signal at exactly 14MHz, it will have a reading between

1. 13.9986MHz and 14MHz
2. 13.9986MHz and 14.0014MHz
3. 13.9993MHz and 14.0007MHz
4. 14MHz and 14.0014MHz

The answer is :- 2

10 parts per 100000 is 100 parts per million,

i.e. 100 Hz per 1 MHz = 1400 Hz per 14 MHz
= 1.4 kHz per 14 MHz

Thus, reading will lie in the range (14 MHz - 1.4 kHz) and (14 MHz + 1.4 kHz), i.e. 13.9986 MHz and 14.0014 MHz.