# Homework Help: Radio waves and charge

1. Jul 29, 2007

### t_n_p

1. The problem statement, all variables and given/known data

AM radio allows a speration of 10kHz between frequencies of different radio stations. Why do AM radio receivers need a large Q? Estimate the Q required for good AM reception.

3. The attempt at a solution

I'm really not sure where to begin!

2. Jul 29, 2007

### Astronuc

Staff Emeritus
3. Jul 30, 2007

### t_n_p

It's not in my textbook but I found out that AM radio receivers need a large q-factor to have a sharper resonance. However I can't find Q required for good AM reception. Any suggestions?

4. Jul 30, 2007

### andrevdh

A electronic oscillator produces em waves at a certain frequency. But the waves are not confined to a particular frequency, instead they spread over a range of frequencies. The most intense radiation (largest power output) is at its resonance frequency. The Q factor quantifies this spread in frequencies. If the stations are too close together the signals from the various transmitters will interfere with the reception.

5. Jul 30, 2007

### t_n_p

Thanks for that more thorough explanation. Still don't know what a good Q is for radio reception though -_-"

6. Jul 30, 2007

### andrevdh

The signals from one station should not overlap with the signal from another station. So you use the given frequency difference between stations to check what the minimum Q factor should be at the mid AM frequency transmissions.

7. Jul 31, 2007