Biology; Chemistry; Physics: Post your doubts here!

[Mayedah]

is there any sort of notes for this?? becoz i havent read this ever!

Same here ...i jst did this mcq and another one...and understood it ...i guess thre os no specific chapter

 

[ashiqbal]

yup its correct i did this paper today and selected D AS THE answer too, i dont think anything special is there u just need to ponder like mad here and see the extensions how they are affected with one spring

i have got so far that for one spring, the extension will be 2x, but cant understand why the same load can produce an extension of 4x in two springs?

 

[asd]

Dude, why will there be large current ? any reason?

 

[Mayedah]

is there any sort of notes for this?? becoz i havent read this ever!

The earth wire is wrongly connected to the live terminal so themetal case willgo live when the current is switched on !

 

[ashiqbal]

i have got so far that for one spring, the extension will be 2x, but cant understand why the same load can produce an extension of 4x in two springs?

oops! i was being a bit stupid there, wasnt i?

 

[ashiqbal]

Dude, why will there be large current ? any reason?

dunno, maybe due to short circuiting between live and earth wire?

 

[Mayedah]

i have got so far that for one spring, the extension will be 2x, but cant understand why the same load can produce an extension of 4x in two springs?

Because of one spring gives 2x thn two springs would give 4x because we add up values in series !

 

[ashiqbal]

The earth wire is wrongly connected to the live terminal so themetal case willgo live when the current is switched on !

I really have to Read this topic carefully!

 

[scouserlfc]

Because of one spring gives 2x thn two springs would give 4x because we add up values in series !

Exactly both springs now extend and now distribution occurs !

 

[asd]

dunno, maybe due to short circuiting between live and earth wire?

Make your point clear first, You're saying that There will be short circuit because insulation will melt and earth wire and live wire will interact to cause a fire. And then you mention that there will be alarge current to melt the insulation, where did that large current come from?

 

[Mayedah]

I really have to Read this topic carefully!

Do nov 2008 paper 1 mcq no 9 related to extension and load !

 

[ashiqbal]

Make your point clear first, You're saying that There will be short circuit because insulation will melt and earth wire and live wire will interact to cause a fire. And then you mention that there will be alarge current to melt the insulation, where did that large current come from?

i am saying that as the earth wire and live wire are connected at the same point, so a large current will flow through them.
.
Anyway forget this arguement, where i know i am wrong and please if someone could explain the mechanics, please do that why the case becomes live?

 

[scouserlfc]

Make your point clear first, You're saying that There will be short circuit because insulation will melt and earth wire and live wire will interact to cause a fire. And then you mention that there will be alarge current to melt the insulation, where did that large current come from?

Which ques is this ??

 

[Fallen316]

People, explain the ques below

A, use the formula 1/R = 1/R1 + 1/R2 + 1/R3

 

[Mayedah]

i am saying that as the earth wire and live wire are connected at the same point, so a large current will flow through them.
.
Anyway forget this arguement, where i know i am wrong and please if someone could explain the mechanics, please do that why the case becomes live?

Case becomes live in the case when there is no earthing of the appliance and if the metal case becomes live and it touches the case if its nt screwed on properly so the large current will not go to earth , instead it will be flow thru the appliance and shock may occur to the user !

 

[ashiqbal]

Do nov 2008 paper 1 mcq no 9 related to extension and load !

its A) 0.5 right?

 

[scouserlfc]

i am saying that as the earth wire and live wire are connected at the same point, so a large current will flow through them.
.
Anyway forget this arguement, where i know i am wrong and please if someone could explain the mechanics, please do that why the case becomes live?

If u guys are talking abt that vaccuum cleaner wala MCQ in J09 then answer is B there
The case becomes live `

 

[convent2012]

1 kg water in a 500g glass beaker is at room temperature ie; 25degreeC. what should be the mass of water at 65degreeC, which is added to beaker to bring its temperature to 40degreeC (c for beaker = 5615J/kg K-1 , c for water = 4200 J/kg K-1 ) ???

 

[Mayedah]

its A) 0.5 right?

Correct

 

[convent2012]

1 kg water in a 500g glass beaker is at room temperature ie; 25degreeC. what should be the mass of water at 65degreeC, which is added to beaker to bring its temperature to 40degreeC (c for beaker = 5615J/kg K-1 , c for water = 4200 J/kg K-1 ) ???

explain plz ..

 

[ashiqbal]

Case becomes live in the case when there is no earthing of the appliance and if the metal case becomes live and it touches the case if its nt screwed on properly so the large current will not go to earth , instead it will be flow thru the appliance and shock may occur to the user !

Ohk!! got it now! thank you very much!!!