# Stationary waves AS level

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#1
My textbook says that is you create a stationary wave with microwaves, there is no signal at the nodes. Why is this?
My notes also say that of you create a stationary wave with sound waves, the sound is louder at nodes and hardly any sound at anti nodes. I understand this is something to do with the pressure at nodes and anti nodes. But why is this different to the microwaves?
0
2 months ago
#2
(Original post by user342)
My textbook says that is you create a stationary wave with microwaves, there is no signal at the nodes. Why is this?
My notes also say that of you create a stationary wave with sound waves, the sound is louder at nodes and hardly any sound at anti nodes. I understand this is something to do with the pressure at nodes and anti nodes. But why is this different to the microwaves?
I think you might have got it wrong - if you sketch a stationary wave the anti nodes are the maximums and the nodes are the zeros. You detect maximum sound or microwaves at the anti nodes and minimum at the nodes.

There's a bit of complexity with standing sound waves in pipes... you get a node at the closed end and an anti node at the open end - I wonder if that's what's confused you.
1
2 months ago
#3
(Original post by user342)
My textbook says that is you create a stationary wave with microwaves, there is no signal at the nodes. Why is this?
The "why is this?" is referring to the creation of stationary wave with microwave or no signal at the nodes.

(Original post by user342)
...My notes also say that of you create a stationary wave with sound waves, the sound is louder at nodes and hardly any sound at anti nodes. I understand this is something to do with the pressure at nodes and anti nodes. But why is this different to the microwaves?
The difference is due to the type of wave and how do we detect the sound and signal for the 2 types of waves.

As sound is a longitudinal wave, we tend to detect the sound based on fluctuation of pressure. In a stationary sound wave, a displacement node is a pressure anti-node while a displacement antinode is a pressure node. So we tend to hear a loud sound at the pressure anti-node which is a displacement node.

However, microwave is an electromagnetic wave and a transverse wave. In a stationary microwave, there is only "displacement" node and anti-node based on the strength of the electric field.
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