Physics, Chemistry and Biology: Post your doubts here!

[always-smile :)]

The molecules can't rise at D, there's no place for them to go up.
At C they go up the tube.

oohh .... thnx guys

 

[ZainH]

Umm which question guys?

Physics paper 1, w06 Q 18.
We found out the answer though.. you can confirm it if you want

 

[GetSomeLife]

That is one of the easiest questions in the history of questions

 

[ZainH]

That is one of the easiest questions in the history of questions

It was a pretty straight forward answer.. I just didn't think of it x)

 

[GetSomeLife]

It was a pretty straight forward answer.. I just didn't think of it x)

It's ok Happens with everyone Like i forgot what was radiation yesterday

 

[always-smile :)]

There are 2 resistors in the circuit (when the switch is in position A) the 22 ohms and the 2 ohms! Both are connected in series so the total resistance will be:
Rt = R1 + R2 = 22 + 2 = 24 ohms

ii)
Total resistance = (R1*R2)/(R1+R2)
R1 is 22 + 2 = 24 ohms
R2 is 8 ohms

We use this formula because they are in parallel:

=(8*24)/(8+24)
= 6 ohms

-------------------
i think this ans. is wrong ... in the ms i-2 and ii- 24

 

[ZainH]

It's ok Happens with everyone Like i forgot what was radiation yesterday

Hahaa, I've got a quick question. Could you explain the difference between an AC generator and a DC motor. (Other then the fact ones AC and the others DC :S )

 

[IGCSE O/L student]

That is one of the easiest questions in the history of questions

it is 4 u, but not for all. not evry1 here is a genius lyk u, includin myself!

 

[ZainH]

Anddd how to magnetise/demagnetise a magnet using a coil and different forms of current (AC/DC)

 

[GetSomeLife]

Hahaa, I've got a quick question. Could you explain the difference between an AC generator and a DC motor. (Other then the fact ones AC and the others DC :S )

In an AC generator, MOTION in a MAGNETIC FIELD (due to rotation of the coil) produces CURRENT!
In a DC motor, CURRENT (probably DC) in a MAGNETIC FIELD produces MOTION!

Hope you got me That's the basic difference... i could say more if you want me to

 

[GetSomeLife]

it is 4 u, but not for all. not evry1 here is a genius lyk u, includin myself!

I never said i am a genius Besides, i said it happens with everyone In my prems exam, i forgot what were the fleming rules

 

[ZainH]

In an AC generator, MOTION in a MAGNETIC FIELD (due to rotation of the coil) produces CURRENT!
In a DC motor, CURRENT (probably DC) in a MAGNETIC FIELD produces MOTION!

Hope you got me That's the basic difference... i could say more if you want me to

Ah k yeah I understood now, thanks. What about the other question? :S

 

[GetSomeLife]

Anddd how to magnetise/demagnetise a magnet using a coil and different forms of current (AC/DC)

To magnetize:

1) The stroking method:
You take a magnet and the metal you want to magnetize and stroke the magnet on it until it becomes a magnet

2) This is the better method: Electrical method:
You place the metal you want to magnetize in a solenoid and then pass a large DC current through it!

To demagnetize:

The most effective method is:
Place the magnet in a solenoid. Then SLOWLY WITHDRAW the magnet from the solenoid AS a large Ac current is passing through it!

 

[ZainH]

To magnetize:

1) The stroking method:
You take a magnet and the metal you want to magnetize and stroke the magnet on it until it becomes a magnet

2) This is the better method: Electrical method:
You place the metal you want to magnetize in a solenoid and then pass a large DC current through it!

To demagnetize:

The most effective method is:
Place the magnet in a solenoid. Then SLOWLY WITHDRAW the magnet from the solenoid AS a large Ac current is passing through it!

Finally an easy definition of this.
Thanks alot x)

 

[IGCSE O/L student]

Anddd how to magnetise/demagnetise a magnet using a coil and different forms of current (AC/DC)

magnetise usin dc, n keep da magnet inside da coil. demagnetise by usin ac, n take da magnet out.

 

[IGCSE O/L student]

I never said i am a genius Besides, i said it happens with everyone In my prems exam, i forgot what were the fleming rules

LOL! i ws jst kiddin.

 

[always-smile :)]

sorry but i have a question which i always forget ...... what's a live wire?

 

[GetSomeLife]

There are 2 resistors in the circuit (when the switch is in position A) the 22 ohms and the 2 ohms! Both are connected in series so the total resistance will be:
Rt = R1 + R2 = 22 + 2 = 24 ohms

ii)
Total resistance = (R1*R2)/(R1+R2)
R1 is 22 + 2 = 24 ohms
R2 is 8 ohms

We use this formula because they are in parallel:

=(8*24)/(8+24)
= 6 ohms

-------------------
i think this ans. is wrong ... in the ms i-2 and ii- 24

Yeah i noticed my mistake and corrected it
However, the answer of ii is 6 ohms

 

[IGCSE O/L student]

sorry but i have a question which i always forget ...... what's a live wire?

it is da wire dat carries da current to da appliance

 

[Mohamed Elfadil]

DOUBTS IN SYALLABUS.... PLEASE ANSWER!!!!!!
1-adv. and disadv. for methods of production of electricity in terms of cost,reliability,scale and environmental impact
2-safety issues regarding th use of microwaves and x-rays
3-recall and use the simple electron model to distinguish betweein conductors and insulators
4-state the qualitative variation of the strength of the magnetic field over salient parts of the pattern
5-describe an experiment to show the corresponding force on beams of charged particals

PLEASE HELP!! MAY ALLAH GIVE GOOD DEEDS