Physics MCQ, June 2002

[abcde]

AOA everyone!
I need help with question 37 : http://www.xtremepapers.net/CIE/Cambrid ... 2_qp_1.pdf
Can anyone explain WHY the correct answer is D?
Thank you!

 

[Nibz]

D, because the other three factors would have the same affect on all the houses!

 

[leosco1995]

Yeah, I hope you read the question carefully because it looks pretty straightforward.

 

[abcde]

Ummm...(excuse me for being stupid) but why isn't it C? I was originally of the opinion that background radiation is the same everywhere.

 

[Nibz]

You can make this assumption that beyond 10 miles there won't be much radiation (or the other four houses might be comparatively near that station); but you CANNOT make any assumption for part D. As it's quite clear!
Hope this helped!

 

[abcde]

So 10 miles is too great a distance to allow any radiation to enter the house and cause a change in the radioactivity count? Ok, that made sense. Any more suggestions?

 

[Nibz]

^ I've edited that post! (Another possibility)
But you always go for the most OBVIOUS MCQ. And you see, there can be many possibilities for Part C. Tou just ignore it!

 

[scouserlfc]

Lock this topic Nibz its going to be a free chat zone if u dont.

 

[abcde]

No, it's not! no comment on this thread was the least irrelevant or off topic! :|
I want more suggestions if there are any so Nibz don't do that! I am especially waiting if leosco1995 has any explanation to give.

 

[Nibz]

Lock this topic Nibz its going to be a free chat zone if u dont.

What made you say that? :ugeek:
And abcde, you're still stuck at this OMG!

 

[OakMoon!]

In O'levels there are two sources of radiations. First is the Cosmic radiations from space and second is background radiations coming from rocks on earth. As far as this question is concerned there is no other liable option. You can't be certain about the nuclear power station. It's not necessary that there is a leakage. 10 miles is not that large a distance to prevent radiations coming to the house. But I don't think nuclear power stations radiate until some problem occurs.

 

[abcde]

@Nibz: not stuck anymore but a little further clarification always helps!

 

[leosco1995]

hamidali391 explained it pretty well. Even if there was a leakage you can't be sure that only house A will be affected. Always go with the option you are most sure of.

Also, I have a question of my own (I didn't want to make a new thread).

Why is the answer of Q26 in this paper not A?

 

[Nibz]

Hahaha .. this time you didn't read the question carefully!

From Diagram 1, find the resistance of the resistor. It'd be => 6 ohms
There are two such resistors in parallel in Diagram 2. Find out their total resistance. It'd be 3 ohms!
Since V remains constant in parallel circuit, your V would remain 3 volts! V=IR => V=3 volts; R= 3ohms.. simply find the current!
It'd be 1 A!
so the answer is simply D

 

[abcde]

Exactly Nibz!

 

[leosco1995]

Right. Thank you guys.

 

[Sehrish]

Just to add a little,
In a parallel network, current increases if more resistors are added and voltage remains the same in any condition whatsoever. So the answer is D.