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# GCE O Level 2011 Oct/Nov Physics 5058 (MCQ) Paper 1 Suggested Answers & Solutions

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Tuition given in the topic of Little Miss Loi the Science Tutor (archived) from the desk of at 9:38 am (Singapore time)

Updated on

Hello again everyone,

After having taken possession a certain booklet, I’m sitting in my sister’s car, looking up at the bright blue morning sky, while sending out this series of codes:

 Q1-10 CCBCB AACCB Q11-20 DCBDB CBADA Q21-30 ACABC BCBAB Q31-40 DCBDA BDDAD

Note: Answer for Q33 has been changed to B. Sorry for the misinformation! 🙁

Do they tally with yours?

Update: The list of workings and explanations for each of the answers (where applicable) have been compiled (along with the questions at the end)!

You may access here by clicking the button (if you haven’t yet done so).

2011 O-Level October/November Physics 5058 Paper 1 Suggested Solutions

Hopefully this will help in some way to settle some of the debates regarding some of the answers (and hopefully not create more in the process!)

Good luck for those of you with your remaining Science MCQ papers! ALMOST THERE!!!

### Revision Exercise

To show that you have understood what Miss Loi just taught you from the centre, you must:

1. YQ commented in tuition class

2011
Nov
11
Fri
10:05am

1

for ques 11, I thought that the answer should be B? cuz only a stretched spring will have elastic potential energy... so at Q is potential and at P is kinetic?

2. Wong Xin Hui commented in tuition class

2011
Nov
11
Fri
10:17am

2

Hello. Thank you for providing answers(: However, I thought for question 6, the answer should be A? Only when all the arrows point in one direction, there will be no resultant force. As the nail does not move, so, that means there is no resultant force, right? (:

3. HP commented in tuition class

2011
Nov
11
Fri
10:20am

3

Why is Q6 D? Shouldn't it be A? Since the nail does not move.

4. Nguyễn Dũng commented in tuition class

2011
Nov
11
Fri
10:26am
5. Rachel commented in tuition class

2011
Nov
11
Fri
10:30am

5

Can you relook Q30? I thought current passes through only one resistor. And also for Q37, cos I still get answer D.

• 2011
Nov
11
Fri
10:48am

5.1

@Rachel: For Q30, answer is B as the current comes out from the alternating current supply, it can go through all four resistors if it travels in the clockwise direction, but when in the anti-clockwise direction the current cannot pass through the resistors which are along the same route as the diode.

Hence only 2 resistors carry the current in 2 directions, and the resistors adjacent to the diode carry current in ONE direction only

As for Q37, the answer is amended to D - thanks for highlighting!

*drawing a diagram to illustrate now*

...

6. fb commented in tuition class

2011
Nov
11
Fri
10:38am

6

For qn37, I calculated the voltage and got D as my answer. How to calculate the voltage for qn37?

7. fb commented in tuition class

2011
Nov
11
Fri
10:42am
8. hi commented in tuition class

2011
Nov
11
Fri
10:48am

8

hi:) thx for the ans but i i ask why qn 37 is b instead of d??

9. Jay commented in tuition class

2011
Nov
11
Fri
10:51am

9

Can someone do an explanation for 37?

Using Np/Ns = Vp/Vs, my best guess is B
Vp/Vs = 12V/6V = 2
So... Np/Ns must be 1000/500 = 2

~

10. hy commented in tuition class

2011
Nov
11
Fri
10:51am

10

should question 33 be B?

When a person touches the live wire the fuse will not blow as a person has a very high resistant. Hence, the current flowing should be low.

11. Ng Thengwei commented in tuition class

2011
Nov
11
Fri
10:57am
12. anonymous commented in tuition class

2011
Nov
11
Fri
11:20am

12

if the answers here are right, my mark should be 37/40 which should be alright. I have a question though. For question 39, my friends say the answer is option B but i wrote option D which tallies with your answer. Can you explain question 39? I don't really understand. And for question 36, why is the answer B? Please enlighten me. THANKS!

13. IP commented in tuition class

2011
Nov
11
Fri
11:33am

13

For question 23, answer is A because the ray bends inwards aft passing through the lens?

14. Jeffrey Lim commented in tuition class

2011
Nov
11
Fri
11:38am
15. ces commented in tuition class

2011
Nov
11
Fri
11:56am

15

16. Hazle commented in tuition class

2011
Nov
11
Fri
11:58am

16

Hi Miss Loi. For question 38, why will the brightness of L1 remain the same(option D)? Since current flowing through L1 decreases when the resistance of the LDR decreases.

• 2011
Nov
11
Fri
12:05pm

16.1

@Hazle: The brightness of the lamp is dependent on the potential difference across the lamp, which is held constant by the battery connected in parallel to it.

Though the resistance is changed in the circuit, the current flowing though the resistors also changes, so it's a better gauge to look at p.d instead of current.

• 2011
Nov
11
Fri
12:11pm

• 2011
Nov
14
Mon
12:43pm

SQhi objects!

Just so you, know, guys, I took the same paper =)

IMHO, the brightness of the bulb should be dependent on the power output of the bulb, and we know that P=IV

I assume everyone has a copy of the paper here.

Let's call the branch on the left with L1 Branch A, and the branch on the right with resistor R & L2, Branch B.

Miss Loi, as you have stated, since Branch A and Branch B are parallel, they would have the same pd as the emf of the battery remains unchanged.

Hence, the decisive factor should be current instead.

Now, as light intensity increases, resistance of R decreases, thus, the overall resistance of the circuit decreases. The resistance of Branch B also decreases, and the current flowing through Branch B increases.

Hence, as Branch B draws a greater current, the current Branch A draws decreases. Hence, by P=IV, the brightness of bulb L1 would decrease.

Oh well, one more bio and one more literature paper to go. JY everyone!!!

P.S.:
If you wonder why the brightness of L2 decreases, as resistance of R decreases, the pd across r decreases (Little Miss Loi edit: you mean increases?) hence pd across L2 increases, leading to higher power output. It's kind of "common-sensical" anyway=)

• 2011
Nov
14
Mon
5:01pm

@SQhi: Little Miss Loi objects!!!!!

Yes, as SQhi has said, the brightness of the bulb ultimately depends on its power which in turn is dependent on the current flowing through it.

Now, as light intensity increases, resistance of R decreases, thus, the overall resistance of the circuit decreases. The resistance of Branch B also decreases, and the current flowing through Branch B increases.

This is true BUT this reduced overall resistance will also lead to an INCREASE in the overall current drawn by the circuit.

Hence, as Branch B draws a greater current, the current Branch A draws decreases. Hence, by P=IV, the brightness of bulb L1 would decrease.

Yes Branch B will definitely draw a greater current due to the reduced resistance of R, so L2 will increase in brightness.

However, Branch A's current will remain the same given that 1) its pd is unchanged 2) the resistance of L1 is unchanged. So by Ohm's Law, the current through Branch A remains unchanged as well.

I've taken the liberty to sub in some arbitrary p. d. and resistance values just to demonstrate this. As you will see, Branch A's current stays constant due to the increased overall current drawn by the circuit, even though Branch B's current has increased.

In short, Ohm's Law will always sort itself out 😉

P.S. This reminds me to update the pdf file - there's a typo for the answer to Q38!

• 2011
Nov
14
Mon
8:45pm

Opps, typo in my post-note, sorry!(thanks for the correction!)
Anyway ya, that was for other visitors, not you =)

D= I have never considered Q38 from that angle...

D= My O level physics is in jeopardy!!! Serious, nerve-wracking jeopardy...

Yet, it feels so good to finally understand this, coz i expect myself to...

Anyway could you let me know how to type subscript and superscript in these comments, and how I could edit my own posts?

17. Zhi Jie commented in tuition class

2011
Nov
11
Fri
12:00pm

17

i believe qn 22 and 23 are wrong. qn22 shld be B since is sin (air) / sin ( glass) =1.5 and qn we shld be C since its converging lens while the other 3 options are all diverging lens

18. Sad day commented in tuition class

2011
Nov
11
Fri
12:29pm
19. Jolene Lim commented in tuition class

2011
Nov
11
Fri
12:37pm

19

Shouldn't the last question answer be 'C' because they are asking you about the frequency of the input of the cro, so it should be only about the screen and not counting the number of waves.

20. fb commented in tuition class

2011
Nov
11
Fri
12:55pm
21. anon commented in tuition class

2011
Nov
11
Fri
12:58pm
22. Ian Pang commented in tuition class

2011
Nov
11
Fri
2:50pm

22

HI... can u explain to me why the ans for qn 33 is C? thks:)

23. Cheryl commented in tuition class

2011
Nov
11
Fri
5:51pm

23

ARGH.. i feel very extremely stupid after looking at this.. and how come everyone's so smart...

24. Dannie commented in tuition class

2011
Nov
11
Fri
5:52pm

24

qn11: my ans was C---becos when u move down spring, elastic potential stored at Q. When u release it is converted to kinetic energy, so at P gt kinetic energy.

25. Benson Dannie commented in tuition class

2011
Nov
11
Fri
6:00pm

25

for qn 26, i got D as answer.
becos Npole created in left of solenoid and south pole at right side.
so, poles induced in rods should be opoosite to poles in solenoid.
eg. Pshould be south, which is opposite to noth pole of solenoid.
so, i gt D as ans. pls comment ty

26. Dennis commented in tuition class

2011
Nov
11
Fri
8:55pm

26

Hi, for question 33, could you explain why the option is C and not B?? Much appreciated!

27. Skyhigh commented in tuition class

2011
Nov
11
Fri
9:24pm

27

Hi Miss Loi, can you explain your ans for qns 33 please.. i chose A too

28. Chloe commented in tuition class

2011
Nov
11
Fri
10:29pm
29. Loi commented in tuition class

2011
Nov
11
Fri
11:09pm
30. marc commented in tuition class

2011
Nov
12
Sat
5:19am
31. Poo commented in tuition class

2011
Nov
12
Sat
9:04am

31

For question 33, i checked the internet and the answer should be B... It does not blow for the first three cases and blows for the last 2. When the person touches the live wire, however, he gets an electric shock but the fuse does not blow. I found the exact question here... http://sg.answers.yahoo.com/question/index?qid=20100312012525AA1rEAC
Can you help to confirm this? Thanks

32. radha commented in tuition class

2011
Nov
12
Sat
10:21am

32

Hi Ms Loi, i think the ans for qn 33 must be B since as the fourth n fifth option will definitely result in blown fuse but for person touching live wire it's debatable because if current can flow through him with low resistance then the fuse will blow if normal case where resistance is high in human the fuse will not blow.

33. jess commented in tuition class

2011
Nov
12
Sat
10:38am

33

Hi what is the safest mark for this paper?

34. Leon commented in tuition class

2011
Nov
12
Sat
12:48pm

34

Hi, for qn 6, why is the ans A? Pls enlighten thanks 🙂 shouldn't the tension of the string be in the opposite direction as the pull of the string?

35. Little Miss Loi commented in tuition class

2011
Nov
12
Sat
1:26pm

35

Good morning (oops should be good afternoon) everyone!

I'll have to agree with the chorus of protests regarding Question of the Year Q33 and changed the answer to B (sorry for the misinformation!)

The main issue here is whether the 3A fuse will blow if a person touches the live wire.

A typical home appliance say, a kettle, will typically have a resistance of around 20-50 Ω, and under normal operation will draw an operating current < 3A (else the fuse will blow).

The human body, on the other hand, will have a resistance of 500 Ω to 1000 Ω to even 1 000 000 Ω (depending on conditions - some researched values are provided here). No matter what value we take, this resistance is at least a few orders of magnitude higher than the resistance of typical appliance and hence will draw a lower current to flow to it.

But since a current as little as 10 mA is already enough to cause an electric shock, the person who touches the live wire will, in all likelihood, turn into Street Fighter Blanka suffering an electric shock with the fuse staying helplessly intact (as shown in the diagram below)!

36. Bell commented in tuition class

2011
Nov
12
Sat
4:35pm

36

Why is qn 39 a? Shouldn't it be b since the thermistor can decrease it's resistance to 0 as it is heated? So houldnt the output voltage decrease to 0 as it's heated?

• 2011
Nov
13
Sun
11:40pm

36.1

@Bell: All thermistors have an operating temperature range which in turn will determine each of their upper and lower resistance limits.

The lower resistance limit, however, will never be zero due to the makeup of its electrical components and materials. If you dwell deeper, you'll find that the relationship between resistance and temperature is actually exponential.

And if you were to Google "thermistor resistance vs temperature chart" and view the images, you'll see in all the graphs that, given the exponential nature of this relationship, the resistances approaches zero as temperatures increases but will never reach zero.

37. sammy commented in tuition class

2011
Nov
13
Sun
9:20am
38. Casper commented in tuition class

2012
Apr
16
Mon
7:59pm

38

I found this really useful...

I was looking for the Physics 5058 2011 question paper but I couldn't find it.. Can some one please tell me where it is?

Thanks

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