What Is the Wavelength of the Signal Based on Goniometer Measurements?

[Mnemonic]

Homework Statement

Initially your receiver is positioned at a distance of 8.4 cm from the goniometer and recording a maximum intensity. You move it through 10 minimums in the intensity and then stop at the next maximum intensity. The receiver is now a distance of 27.3 cm from the goniometer.

What is the wavelength of the signal you have measured?

Homework Equations

ƛ/2=Distance between two maximums

The Attempt at a Solution

ƛ=2(27.3-8.4)cm
=37.8cm

It's that simple right?
I keep getting the wrong answer with this. What am I missing?

 

[haruspex]

Homework Statement

Initially your receiver is positioned at a distance of 8.4 cm from the goniometer and recording a maximum intensity. You move it through 10 minimums in the intensity and then stop at the next maximum intensity. The receiver is now a distance of 27.3 cm from the goniometer.

What is the wavelength of the signal you have measured?

Homework Equations

ƛ/2=Distance between two maximums

The Attempt at a Solution

ƛ=2(27.3-8.4)cm
=37.8cm

It's that simple right?
I keep getting the wrong answer with this. What am I missing?

You are not taking into account that it was moved through many minima and maxima. You have calculated as though it was moved to the very next maximum.

 

[Mnemonic]

You are not taking into account that it was moved through many minima and maxima. You have calculated as though it was moved to the very next maximum.

The wording in the question confused me. So you are saying that between each of the 10 minimums there was a maximum as well?

 

[haruspex]

The wording in the question confused me. So you are saying that between each of the 10 minimums there was a maximum as well?

That's the usual arrangement.

 

[Mnemonic]

That's the usual arrangement.

SO there are 5 complete wavelengths.

Therefore ƛ=(27.3-8.4)/5 cm

 

[haruspex]

SO there are 5 complete wavelengths.

Therefore ƛ=(27.3-8.4)/5 cm

That looks better.