A wrong question n past 3 papers (1 Viewer)

[Comedy_Al]

In the past 3 hsc papers, there was a question involving a mobile phone, connected to a laptop in 2000,2001, and you had to identify the mode of transmission. The given answer said Radio waves, But mobile phones use Microwaves- hence the issues with brain cancer. Should someone ring up and inquire?

 

[Huy]

I'd just leave it alone, depending on if it was multiple choice, or if it were short answer (Q21-24).

If it was multiple choice, and I had seen it in 2000, 2001 and as well as 2002, whilst sitting for my 2003 HSC, I would answer Radiowaves, unless I thought otherwise (depending on the day/mood )

I haven't seen the exact wording/diagram, so I'll go on what you've stated. As long as you know that the marking criteria/guidelines are looking for radio waves as an answer, you might as well get 1-2 marks (even if it is wrong), unless, of course, there are hundreds of other IPT kids who would disagree

 

[Lazarus]

Q6 in 2001 and Q22 in 2002 (there are minor differences between the two).

I'm looking into it...

 

[Huy]

Originally posted by Lazarus
Q6 in 2001

6 A passenger in a car travelling in country New South Wales phones a friend in Sydney. The diagram shows how the call could be transmitted through the telephone system.

| Segment 1 | Segment 2 | Segment 3 | Segment 4 |

3.5km, 120km, 260km, 15km,

Car to Telephone Exchange (Regional NSW), to
Repeater stations/microwave tower it looks like, to
Telephone Exchange at Orange, to
Telephone Exchange at Sydney, to
Home in Sydney.

What transmission media, in order from Segment 1 to Segment 4, would be most appropriate?

(A) Microwave, microwave, optic fibre, twisted-pair cable
(B) Radio, microwave, optic fibre, twisted-pair cable
(C) Radio, radio, twisted-pair cable, coaxial cable
(D) Radio, microwave, twisted-pair cable, coaxial cable.

Now, just looking at the diagram and the distances, you can already see that C and D are not correct, because they have twisted-pair cabling between Telephone Exchanges, and I believe they are always fibre optic. Also, they have coaxial cabling from the Telephone Exchange to the Home, spanning 15km. The cabling which is normally used is twisted-pair cabling (split your telephone line cross-sectionally and you will see two twisted pairs, not that I am telling you to do so )

So that leaves (A) or (B).

The "ends" of both answers, optic fibre and twisted-pair cable are correct, as well as from Segment 2 to Segment 3 (microwave).

I would have to say A is the most correct answer, as microwaves are transmitted from the mobile phone, from the car, and it is only a reasonably short distance of 3.5km between Segment 1 and Segment 2 anyway, to the Telephone Exchange in Regional NSW.

Originally posted by Lazarus
Q22 in 2002

This question, I have answered in another thread (a while back). Search for "Jill" and "mobile technology" in the IPT forum.

Data Redundancy + Mobile tech
http://www.boredofstudies.org/community/showthread.php?s=&threadid=10053

/edit, looks like this person only asked for 22(b), not the entire Question 22.

22
(a) For EACH segment, identify ONE appropriate transmission medium and outline why each one is appropriate. (4 marks).

Segment 1
- Laptop connected to mobile phone
- 3.5km across a country town

Segment 2
- country telephone exchange to microwave tower
- 120km across mountains

Segment 3
- country telephone exchange to sydney telephone exchange
- 260km across rural and suburban areas

Segment 4
- sydney telephone exchange to head office building
- 15km across city area

4 mark question, so I guess it is 1 mark per segment, assuming the student has given correct answers. That is, appropriate transmission mediums and logical/appropriate reasoning behind choice of medium. (per segment, for the 1 mark, for the full 4 marks, you would need all segments (1-4) answered correctly with reasoning).

Segments 1 and 2 are wireless, so you have a few choices:

- Microwave
- Satellite
- Mobile Phone/Wireless LAN

Segments 3 to 4 are wired transmission mediums, so you will select one of the following:

- Twisted-pair cable(s)
- Coaxial cable
- Fibre-optic cable

Once you've established that, take a close look at the distances involved, noting the benefits, advantages/disadvantages of each transmission medium aforementioned.

Segment 1
- 3.5km
- Wireless transmission
Mobile phones using radio signals to be sent through air and space. It doesn't need a physical fixed connection so the laptop and mobile phone can be mobile (which makes sense for a 'mobile' phone ). Data is sent over a grid (cell) linked to the wireless network. They are to be used here as Jill travels across town, spanning 3.5km (or write something else which links back to the scenario).

Segment 2
- 120km
- Wireless transmission
Microwave radio signals (note: 'microwave radio signals' ) are sent through space in a straight line from one antenna to another, in 'line of sight' from one mountain top to another. They are placed on tall buildings, or in Segment 2, high mountain tops to continue the transmission over long distances (that is, 120km). It is faster than telephone lines or coaxial cables, however transmission can be affected due to weather, buildings, trees and so on.

Segment 3
- 260km
- Wired transmission
From a country telephone exchange to a Sydney telephone exchange, twisted-pair cabling would be used as you must remember the large distance (260km) involved. It is not feasible to have 260km of fibre-optics from a rural area to a suburban area, spanning 260km from the inner country to the city. Twisted-pair cabling reduces the amount of interference. It is, however, the slowest transmission medium but can be used across rural and suburban areas (vast expanses of 260km).

Segment 4
- 15km
- Wired transmission
Fibre optic cabling carries a laser of light to carry data and is free from EM/electromagnetic and radio interference. It is used across 'short' distances (of 15km in the question/Segment 4), and is secure/transmits data at high speeds without errors. Fibre optic carries a large bandwidth in excess of 400Mbps and can carry thousands of telephone conversations (or in the Question, Jill's logging on procedure).

Hopefully I've answered your question.

Just make sure to write "A microwave is a high frequency radio signal"

/Edit
Woohoo 2222 posts!

 

[Lazarus]

Nice work, Huy. Here's the answer I received for Q6 in the 2001 paper -

Hi James

I think the logic behind the answer B lies in the actual diagram and
distances involved. Firstly the fact that the signal goes directly
from the car to the exchange without any relay antennae being shown
and secondly because it is only a distance of 3.5km as opposed to
120km in Segment 2.

I think it is one of those questions that you have to set aside
common knowledge and just deal with the facts that have been given.

Hope this helps
Michelle O'Toole
Albury High School

 

[Comedy_Al]

So except for the multiple choice, both radio and microwave would be marked as correct for the mobile phone segment?

 

[Huy]

Originally posted by Comedy_Al
So except for the multiple choice, both radio and microwave would be marked as correct for the mobile phone segment?

I would imagine so, but strictly speaking, microwaves are a form radio waves with a shorter wavelength. (Microwaves have a higher frequency than radio waves).

If all else fails, you can write "Electromagnetic (EM) wave" and they can't argue with that. (I am only joking here ).

If you are still unsure about whether it is "radio" or "microwave", you can always include this opening statement/definition:

"A microwave is a high frequency radio signal". This is what Heinemann (IPT) Text states, so you would still be correcting in saying either microwave OR radio, but make sure you speak about microwaves in terms of radio signals, with a shorter wavelength or higher frequency than 'ordinary' radio waves.

I hope I haven't confused you, or myself.