physics

mathematician

how can plane polarization be expressed usin a tv aerial, and the tv set.
hence the tv aerial includes the reflector, and directional rods.
cheers.

what do you mean by expressed?

Reply 2

an experiment be setup to show how waves r plane polarized usin a tv aerial and tv set.
the only thing i can think of is usin the directional rods of the aerial to plane polarize the microwaves then rotate the dipole ( reciever about 90 degrees and check the tv set )
but im not sure, becos the directional rods r in such a position where polarizing incoming microwaves will be difficult

Incoming wave directional rods Dipole receiver reflector Tv set
----------------> |||||||| : | []

Reply 3

Are radio waves in TV signals not polarised anyway?

Reply 4

you can rotate the aerial 90 degrees and get a weaker/stronger signal.

hitchhiker_13

Are radio waves in TV signals not polarised anyway?

They are polarised.

Reply 5

elpaw

They are polarised.

So, maybe I'm being stupid here, but can't you just rotate aerial, and you get a weak, or no, signal?

Reply 6

u cant just rotate the aerialcos how r u polarizing the waves?

Reply 7

mathematician

u cant just rotate the aerialcos how r u polarizing the waves?

are you using the same aerial to create AND detect the signal?

Reply 8

mathematician

u cant just rotate the aerialcos how r u polarizing the waves?

Do you have to polarise the waves or show that they are polarised?

(Edit: This goes back to Elpaw's question, what do you mean by expressed?)

Reply 9

either will help me understand?

Reply 10

mathematician

yes u are,
but hold on uve got natural unpolarized waves coming to the aerial yer?
how are they being plane polarized in the first place?

I'm not sure. Aren't they just passed through a polarising lens?

Reply 11

mathematician

either will help me understand?

OK, can you just go through your experiment, or tell us what you have been asked to do (i.e. if this is for an exam, tell us what they have written)

Reply 12

i think it has something to do with the directional rods acting as parrallel grilles to polarize the wave, then they are polarized, to which u can rotate the reciever 90 degrees to check if they are polarized but im not sure at all!

Reply 13

it just says OUTLINE how u can demonstrate experimentally, using the aerial and tv set, that the incoming wave was plane polarized?

Reply 14

Well, if you imagine waves like this with vertical axis polarisation ^^^^^^ (sorry it's the best i can do) approaching an upright aerial like this l

^^^^^^^^^^l (head on view)

Well if you rotate the plane of polarisation, the aerial won't pick up the signal properly, because the waves won't be hitting the aerial.

So if you had horizontal axis polarisation, it would look a bit like this from above

^^^^^^^^^^^ . (aerial appears as point)

I'm sorry, I'm not explaining this very well. It would be a lot easier if you could draw diagrams.

Reply 15

mathematician

it just says OUTLINE how u can demonstrate experimentally, using the aerial and tv set, that the incoming wave was plane polarized?

then surely rotating the aerial about the axis parallel to the incoming wave direction will change the signal strength detected.

Reply 16

How many marks is the question worth?
I only ask, because if it's for 2 marks or something, it's unlikely to be anything complicated.

Reply 17

i c wot your saying but how are they vertical plane polarized in the first place where did they get polarized from

Reply 18

erms its on the AEA paper, erm 5 marks but it has another easy part to it
id say tht part is worth about 3 marks

Reply 19