Path Difference: Why a Cold Spot Forms at S

In summary, the conversation is about a question on a past paper that involves calculating path difference to explain why a cold spot is formed in microwaves. The question shows waves reflecting off the top and sides of the microwave and the calculation is done by subtracting the distances traveled by the waves. The final step is to divide the result by 12, but the reason for this step is unclear. The question also raises the question of the wavelength or frequency of the microwaves.
  • #1
Luke1121
14
0
I was doing a past paper earlier and i got a question about cold spots in microwaves and i needed to calculate path difference the question was:

---------|------->S<---------|--------- Explain why a cold spot is formed at S
18cm | 6cm. 12cm | 30cm

The question showed the waves reflecting off the top and sides of the microwave which are shown by the -|-

It was 4 marks so a calculation should be done and i did (30+12)-(18+6) then i didnt know what to do, i then found out you are supposed to divide (30+12)-(18+6) by 12. But I am not really sure why, can anyone explain why? Thanks
 
Physics news on Phys.org
  • #2
What is the wavelength or frequency of the microwaves?
 

Related to Path Difference: Why a Cold Spot Forms at S

What is path difference?

Path difference is the difference in distance traveled by two waves originating from the same source and reaching a specific point. It can be calculated by finding the difference in the lengths of the paths the waves take to reach the point.

Why does a cold spot form at S?

A cold spot forms at S because of destructive interference between the two waves reaching that point. This means that the waves are out of phase and cancel each other out, resulting in a decrease in amplitude and therefore a decrease in temperature.

How is path difference related to interference patterns?

Path difference is a crucial factor in determining interference patterns. When the path difference between two waves is an integer multiple of the wavelength, constructive interference occurs and results in a bright spot. When the path difference is a half-integer multiple, destructive interference occurs and results in a dark spot.

Can path difference be negative?

No, path difference cannot be negative because it is a measure of the difference in distance traveled and distance cannot be negative. However, it can be zero if the two waves reach the point in phase, resulting in constructive interference.

How does the wavelength of the waves affect path difference?

The wavelength of the waves directly affects the path difference. A longer wavelength means a greater path difference, while a shorter wavelength means a smaller path difference. This is because the wavelength is a factor in calculating the length of the paths the waves take to reach a specific point.

Similar threads

Progressive wave, wavelength moving in the opposite direction
    • Introductory Physics Homework Help
Replies
4
Views
933
Radio waves in air and water - difference in path
    • Introductory Physics Homework Help
Replies
1
Views
927
Sound Wave Interference and Finding the Path Differences with Diagrams
    • Introductory Physics Homework Help
Replies
20
Views
2K
Why does diffracted white light have a white central fringe?
    • Introductory Physics Homework Help
Replies
6
Views
5K
Effect of different magnetic fields on a magnetic dipole
    • Introductory Physics Homework Help
Replies
25
Views
323
Electric potential difference in a charge
    • Introductory Physics Homework Help
Replies
11
Views
3K
Why Do Different Paths in a Diode Circuit Show Different Voltages?
    • Introductory Physics Homework Help
Replies
7
Views
2K
Path difference in Fibre Optics
    • Introductory Physics Homework Help
Replies
1
Views
2K
Microwave Interference and Signal Detection: Understanding Homework Question
    • Introductory Physics Homework Help
Replies
3
Views
1K
Showing work is path independent
    • Introductory Physics Homework Help
Replies
6
Views
2K

Hot Threads

Recent Insights

Back
Top