Q&A - PSLE Science

[elkniwt]

Hi Tianzhu,


Thank you very much. Your explanation is very clear and precise. My dd will be able to understand. Thanks!

Regards.

[BigDevil]

If a light bulb is connected to 3 batteries which are arranged in the following sequence:


[- +][- +][+ -]

Will the bulb light up? Note the 2nd and 3rd battery is connected +ve to +ve.

Niece's school teacher says yes. Tutor says no.

:faint:

[atutor2001]

BigDevil:

If a light bulb is connected to 3 batteries which are arranged in the following sequence:


[- +][- +][+ -]

Will the bulb light up? Note the 2nd and 3rd battery is connected +ve to +ve.

Niece's school teacher says yes. Tutor says no.

:faint:

Batteries are still conductor of electricity even when they are \"flat\" (but cannot be damaged like liquid flowing out) or when they are connected wrongly.

When connected wrongly, the voltages of 2 \"opposing\" batteries will \"cancel\" each other. Therefore, the final voltage will be zero if the number of batteries in one direction is the same as the number of batteries in the other direction (voltage of every battery is the same) and no electric current will flow. Current will not flow because there is no Potential Difference (voltage) in the circuit to push electric current round the circuit and not because that the circuit is OPEN. It is still a close circuit.

For your case, electric current can still flow because the net voltage is that of 1 battery. The other 2 batteries that are opposing each other will just act as conductor of electricity. So the teacher is correct.

[isetan]

Hi atutor2001,


I come across such similar like questions in some assessment books. The answer is similar to the tutor’s ans, ie no current will pass thru.

So I think such books also quite misleading.

[Michaelia0816]

Suggests me the suitable words!


Question:
Some of the energy is users by each organism itself to carry out a)______ b)______ such as respiration, movement, digestion and growth.

Thank a million!
( Based on Science Process Skill P5&6 Interaction Enviroment)

[Augmum]

Michaelia0816:

Suggests me the suitable words!


Question:
Some of the energy is users by each organism itself to carry out a)______ b)______ such as respiration, movement, digestion and growth.

Thank a million!
( Based on Science Process Skill P5&6 Interaction Enviroment)

life processes ?

[Michaelia0816]

My answer is basic processes, do u agree

[atutor2001]

isetan:

Hi atutor2001,


I come across such similar like questions in some assessment books. The answer is similar to the tutor's ans, ie no current will pass thru.

So I think such books also quite misleading.

Hi isetan
I agree with you. Quite a number of the assessment books have errors in their answers. Some times we can also find mistakes in the answer keys from schools. I think Primary Science syllabus is a bit too wide and each topic is not covered with enough depth. The range make it very tough for the children to remember and the lack of depth make it difficult for them to understand.

[BigDevil]

atutor2001:

BigDevil:

If a light bulb is connected to 3 batteries which are arranged in the following sequence:


[- +][- +][+ -]

Will the bulb light up? Note the 2nd and 3rd battery is connected +ve to +ve.

Niece's school teacher says yes. Tutor says no.

:faint:

For your case, electric current can still flow because the net voltage is that of 1 battery. The other 2 batteries that are opposing each other will just act as conductor of electricity. So the teacher is correct.

Thanks, atutor2001!

Guess it's time for her to change tutor.

[Michaelia0816]

BigDevil:

atutor2001:

[quote=\"BigDevil\"]If a light bulb is connected to 3 batteries which are arranged in the following sequence:


[- +][- +][+ -]

Will the bulb light up? Note the 2nd and 3rd battery is connected +ve to +ve.

Niece's school teacher says yes. Tutor says no.

:faint:

For your case, electric current can still flow because the net voltage is that of 1 battery. The other 2 batteries that are opposing each other will just act as conductor of electricity. So the teacher is correct.

Thanks, atutor2001!

Guess it's time for her to change tutor. [/quote]Similar like tha magnet, like poles and unlike poles. Haha!