PSLE 2009 - Science

[justsay]

James Ang:

Augmum:

How about the question regarding the addition of the bulb, any1 can remember the diagram?

This question resembles a Pure Physics O levels MCQ question which shows two bulbs arranged in series and then one additional bulb is connected in parallel arrangement to the first bulb and the question ask what happens to the brightness of the second bulb.

The answer will be the first bulb becomes dimmer and the second bulb becomes brighter. The explanation is that the potential difference for the first bulb and second bulb is the same before the additional bulb is connected in parallel to the first bulb. But when the additional bulb is connected, the potential difference (or voltage) of first bulb is reduced and that of second bulb is increased (since the emf of the battery is the same). The fall in voltage for first bulb is due to the lower combined effective resistance as a result of the parallel arrangement of bulbs. Anyway I ask one of my new student preparing for O levels, and he got that question wrong.

My elder daughter is taking O level this year too. She told me she has just done this question last week from the ten years series.

My stress is not over yet....more to come

[justsay]

James Ang:

Augmum:

How about the question regarding the addition of the bulb, any1 can remember the diagram?

This question resembles a Pure Physics O levels MCQ question which shows two bulbs arranged in series and then one additional bulb is connected in parallel arrangement to the first bulb and the question ask what happens to the brightness of the second bulb.

The answer will be the first bulb becomes dimmer and the second bulb becomes brighter. The explanation is that the potential difference for the first bulb and second bulb is the same before the additional bulb is connected in parallel to the first bulb. But when the additional bulb is connected, the potential difference (or voltage) of first bulb is reduced and that of second bulb is increased (since the emf of the battery is the same). The fall in voltage for first bulb is due to the lower combined effective resistance as a result of the parallel arrangement of bulbs. Anyway I ask one of my new student preparing for O levels, and he got that question wrong.

Newspaper reported the maths paper and also the chinese paper compre passage. Don't be surprise if there is another complain about this question from o level syllabus.

[Augmum]

hi james


thks, i understand what u're trying to explain regarding the question, i just wanna to clarify the exact drawing of the circuit diagram of how the wire connection is made after the addition of the bulb.

pl refer to the previous postings below.

anyway, i think the kids' memory now about any science questions is being replaced by computer games. they are only interested in the very day when they checked answers with their fellow mates. to them whether their answers were correct or not is already a past issue but we parents here are still discussing about the questions.........haha, so funny.....

acelancer:

justsay:

Goto http://www.pslescience.blogspot.com

If the question on adding a bulb parallel to one of the bulbs in series was drawn this way, I would agree that the answer should be (2) would be brighter.

the pic of the adding a bulb parallel to one of the bulbs in series question was not like tht. it was another way... but similar.(a small difference may make a great differrence)

Augmum:

My gal also mentioned the diagram looks different. according to her, the added parallel bulb is in the middle and the connection of the wire is extended and connected to the right side (something like that).

any pupil here remembers the exact diagram drawn.

[kohjl]

kohjl:

Augmum:

any1?? plasmastorm, can u remember the above 2 questions?? thks.

Hi Augmum,
I'll ask PlasmaStorm when he comes home. Hope he can remember...but like I said, he only has computer games on his mind right now! Got to curtail that soon as I don't want him to get addicted...

Asked my son about the questions as requested, but like all the other kids, he also has \"PSLE Amnesia\"! :lol:

[turquoise]

Augmum:

hi james


thks, i understand what u're trying to explain regarding the question, i just wanna to clarify the exact drawing of the circuit diagram of how the wire connection is made after the addition of the bulb.

pl refer to the previous postings below.

anyway, i think the kids' memory now about any science questions is being replaced by computer games. they are only interested in the very day when they checked answers with their fellow mates. to them whether their answers were correct or not is already a past issue but we parents here are still discussing about the questions.........haha, so funny.....

acelancer:

[quote=\"justsay\"]Goto http://www.pslescience.blogspot.com

If the question on adding a bulb parallel to one of the bulbs in series was drawn this way, I would agree that the answer should be (2) would be brighter.

the pic of the adding a bulb parallel to one of the bulbs in series question was not like tht. it was another way... but similar.(a small difference may make a great differrence)

Augmum:

My gal also mentioned the diagram looks different. according to her, the added parallel bulb is in the middle and the connection of the wire is extended and connected to the right side (something like that).

any pupil here remembers the exact diagram drawn.

[/quote]My dd says the diagram is not like the one in the picture too. Her description sounds like your daughter's.

If that is the diagram, then what is the correct answer?

[chk707]

kohjl:

Asked my son about the questions as requested, but like all the other kids, he also has \"PSLE Amnesia\"! :lol:

My son can remember most of the Maths only. For Science, he can't remember a single 1! :lol: :

[Tang]

turquoise:

My dd says the diagram is not like the one in the picture too. Her description sounds like your daughter's.


If that is the diagram, then what is the correct answer?

I think Plasmastorm's answer is correct - The bulb in series will be Brighter.

[Augmum]

kohjl:

kohjl:

[quote=\"Augmum\"]

any1?? plasmastorm, can u remember the above 2 questions?? thks.

Hi Augmum,
I'll ask PlasmaStorm when he comes home. Hope he can remember...but like I said, he only has computer games on his mind right now! Got to curtail that soon as I don't want him to get addicted...

Asked my son about the questions as requested, but like all the other kids, he also has \"PSLE Amnesia\"! :lol:[/quote]kohjl, nevermind, thks, understandable.

[Tang]

Vikaesh:

mew2:

[quote=\"Vikaesh\"] See if you can come up with a good answer for it with the picture. :thankyou: !



http://www.postimage.org/

hey, you cant come up with a good ans after the paper??!! unless you are a tutor or need to publish an assessment book for the coming year? LOL...

Sorry, but i meant if you could find out the answer to the Question. It's alright if you can't. Hope someone else will come forward to help. :lol:[/quote]
What is the difference from the picture attached? Vanes all vertical?

1 vane or both vanes turned?

What was the direction of the turn?

[Augmum]

turquoise:

My dd says the diagram is not like the one in the picture too. Her description sounds like your daughter's.


If that is the diagram, then what is the correct answer?

hi turquoise
seems that our daughters have alike minds, they both read and see the same thing, for this circuit question and the butterflies question.

your \"that diagram\" isit refers to the one posted?

if yes, then shd be brighter but if the diagram was not drawn like that, then i think the bulb brightness shd remains the same. how i wish i could see the actual diagram!