Question

Harmonics problem. A square wave of frequency f contains harmonics (sine waves) at f, 3f, 5f, 7f, ... . Suppose a system responds to frequencies in the range 20-40 kHz but is insensitive outside of this range.EXAMPLE:Imagine applying a square wave with f = 30 kHz to this system. What is the shape of the response?[Answer: a 30 kHz sine wave. ]Imagine applying a square wave with f = 10 kHz to this system.What is the shape of the response?A. A 10 kHz sine waveB. A combination of 20, 30 and 40 kHz sine wavesC. A 30 kHz sine waveD. No response

Answer 1

Answer:

B

Explanation:

A square of frequency of consists of the infinite sum of sine waves, whose frequencies are the odd multiples of the main frequency f i.e f, 3f,5f, 7f, ... . Given that the range of frequencies, to which the system responds is 20-40 kHz, for a square wave of frequency 10kHz we need to look for the harmonics whose frequencies are in the systems' respond range, which are the  harmonics of 20, 30 and 40 kHz