Is this accurate?

Question

I need a vague sentense about why AC is used for radio recievers. I came up with this, but i'm not sure if it's accurate.

Radio’s are dependant on the oscillation of electrons in the antenna caused by a radio wave producing AC electricity with a frequency the same as that of the radio wave.

So if i wrote this, i wouldn't get marked wrong?

Answer 1

What do you mean be "AC is used for radio receivers"? If you mean the internal circuits for receiving, detecting and amplifying transmitted signals, then you are on the right track. Only AC electricity will produce electromagnetic waves that travel through space. In addition, any information that is to be transmitted requires a change in some parameter with time (this is called modulation). As soon as modulation is applied, the voltage is no longer plain DC, but has an AC component.

Any information (voice, music) carried by the transmission will be in AC form, since that is how they originated. Therefore even the amplifiers in the radio operate on AC.

If you mean the power source for the radio (line power), that can be either AC or DC. Portable radios operate on DC. It is true that this is usually converted to AC inside the radio; this is because it is generally necessary to change the voltage level, and this is done with transformers which only work on AC.

Answer 2

I'd rewrite it:

"Radios are dependant on the oscillation of electrons in the antenna caused by a radio wave producing an AC signal with a frequency the same as that of the radio wave."

There's nothing fundamentally wrong with your original sentence. It's just better to use the term signal rather than electricity.

Answer 3

Right. I'd also describe why it isn't DC.

Radio recievers/transmitters rely on pulses of information, called electromagnetic waves; Since AC voltage is already pulsing, a circuit can be used to adjust the pulse rate (frequency) to the value you want to transmit at.


With DC, you'd need an inverter, and even then the waves wouldn't be alternating, and you'd get a bunch on phase cancelling.

Answer 4

AC was invented first, the first radios were using AC. They just continued using it until now. AC transmitters on the other hand uses more power than DC so this means it covers a bigger area.

Answer 5

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