Polarisation Question

#1
Hi there, I was just stuck on a question.

OCR Physics Electrons Waves and Photons paper.

http://www.ocr.org.uk/Images/319537-...nd-photons.pdf

Markscheme - http://www.ocr.org.uk/Images/320124-...otons-june.pdf

Question 5 d ii

Q: The detector is rotated 90 degrees about the axis through OQ (what is the effect of the intensity heard.)

How do you know that the signal is (vertically) polarised like the markscheme says, there's no indication of that in the question. Also microwaves are EM waves which are transverse. Thus why does the signal fall to zero?

Your help would be very much appreciated!!!
0
5 years ago
#2
The two speakers are producing plane polarised waves.
0
#3
The two speakers are producing plane polarised waves.

But how do you know that, microwaves are transverse waves which are normally not polarised
0
5 years ago
#4
(Original post by SmurfyZ)
But how do you know that, microwaves are transverse waves which are normally not polarised
The two sources interfere constructively at O; this causes the waves to vibrate in only one plane.

0
5 years ago
#5
(Original post by SmurfyZ)
Hi there, I was just stuck on a question.

OCR Physics Electrons Waves and Photons paper.

http://www.ocr.org.uk/Images/319537-...nd-photons.pdf

Markscheme - http://www.ocr.org.uk/Images/320124-...otons-june.pdf

Question 5 d ii

Q: The detector is rotated 90 degrees about the axis through OQ (what is the effect of the intensity heard.)

How do you know that the signal is (vertically) polarised like the markscheme says, there's no indication of that in the question. Also microwaves are EM waves which are transverse. Thus why does the signal fall to zero?

Your help would be very much appreciated!!!
(Original post by SmurfyZ)
But how do you know that, microwaves are transverse waves which are normally not polarised
I can understand the frustration. I agree that the question is not clearly whether the microwaves are plane-polarised from the source.

My guess is when the question mentions a polariser is placed at the detection point, the transverse waves should be polarised vertically at the source.

You may also want to check with your teacher what are all the necessary conditions for transverse waves to have clear interference pattern. If your teacher include the transverse waves must have same direction of polarisation, then whenever you see such question that involves transverse waves, the waves must be polarised.
1
#6
(Original post by Eimmanuel)
I can understand the frustration. I agree that the question is not clearly whether the microwaves are plane-polarised from the source.

My guess is when the question mentions a polariser is placed at the detection point, the transverse waves should be polarised vertically at the source.

You may also want to check with your teacher what are all the necessary conditions for transverse waves to have clear interference pattern. If your teacher include the transverse waves must have same direction of polarisation, then whenever you see such question that involves transverse waves, the waves must be polarised.
Cheers man, i'll definitely check with my teacher.
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