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Qualification => Subject Doubts => IGCSE/ GCSE => Sciences => Topic started by: gaurav95 on May 04, 2010, 04:07:09 pm

Title: Chemistry, Physics
Post by: gaurav95 on May 04, 2010, 04:07:09 pm
Chem:- What is halide and  halogenation
Phy:-Where do we use left hand rule and Right hand rule(Flemming's)?Can somebody give me some e.g.s on that thx
Title: Re: Chemistry, Physics
Post by: holtadit on May 04, 2010, 04:11:55 pm
A halide ion is a a group 7 ion.

Like chloride Cl- is a halide ion.


Halogenation is basically a substitution reaction between an alkane and any free radical halide.

For example methane reacts with chlorine free radical to form chloromethane and hydrogen chloride.

The essential condition is UV light.
Title: Re: Chemistry, Physics
Post by: Snake on May 04, 2010, 04:17:04 pm
Yea I want to know the same thing for Phy, I don't get it lol
Title: Re: Chemistry, Physics
Post by: Ghost Of Highbury on May 04, 2010, 04:26:26 pm
thuMb represents the motion
Forefinger represents the field
Central finger represents the current..
look at the capital letters...M F C ...motion,field,current..

Right hand rule is used to find the direction of the current in a generator.

Left Hand rule to find the direction of the motion of the wire in a motor.
Title: Re: Chemistry, Physics
Post by: rahuldevnani93 on May 04, 2010, 06:42:53 pm
Left hand rule is applied when current causes motion

Right hand rule is applied when motion causes current...
Title: Re: Chemistry, Physics
Post by: Snake on May 04, 2010, 06:52:19 pm
Examples please?
Title: Re: Chemistry, Physics
Post by: gaurav95 on May 05, 2010, 07:25:55 am
thuMb represents the motion
Forefinger represents the field
Central finger represents the current..
look at the capital letters...M F C ...motion,field,current..

Right hand rule is used to find the direction of the current in a generator.

Left Hand rule to find the direction of the motion of the wire in a motor.

I am sorry to ask this qs but are you sure about your answer :o :o :o :o :o :o :o :o
Title: Re: Chemistry, Physics
Post by: Ghost Of Highbury on May 05, 2010, 08:40:17 am
I am sorry to ask this qs but are you sure about your answer :o :o :o :o :o :o :o :o

yes, very sure
Title: Re: Chemistry, Physics
Post by: holtadit on May 05, 2010, 09:26:28 am
Question 9 C   ii


Why does the wire move towards the thick rigid one ? PLEASE READ THE BELOW PARAGRAPHS FIRST

If the current is flowing down both wires there is a magnetic field going clockwise IN BOTH WIRES, hence shouldnt they deflect ?


OR is it a rule that mag fields that move in the same direction (clockwise/anticlcokwise) interact and hence cause an ATTRACTION
Title: Re: Chemistry, Physics
Post by: Ghost Of Highbury on May 05, 2010, 09:40:39 am
Ok this is tricky, i have to use the image to explain, answer in next post.
Title: Re: Chemistry, Physics
Post by: holtadit on May 05, 2010, 09:47:15 am
Ok this is tricky, i have to use the image to explain, answer in next post.

Thanks man.  :)
Title: Re: Chemistry, Physics
Post by: Ghost Of Highbury on May 05, 2010, 09:49:43 am
Refer to the diagram attached herewith.

The orange line indicates the magnetic field. As u can see it is in a circular form, Now, here u have to use the flemming's left hand rule.

However, as the magnetic field is in circular form u have to choose one point to apply the Left hand rule. The red point marken on the line T3-T4 is that point. (Note - the red point shudve been on the wire (T3-T4), it didnt come up in the image, sry abt that)

Okay, so at that point, the magnetic field is pointing in the direction of the blue arrow (consider it as a tangent to the circle)

The brown arro indicates the current.

If u arrange ur left hand in this form u will see the movement of the wire is towards the thick rigid wire as ur thumb points towards it.

im not sure abt this, astar plz check. thanks
Title: Re: Chemistry, Physics
Post by: holtadit on May 05, 2010, 09:53:30 am
Refer to the diagram attached herewith.

The orange line indicates the magnetic field. As u can see it is in a circular form, Now, here u have to use the flemming's left hand rule.

However, as the magnetic field is in circular form u have to choose one point to apply the Left hand rule. The red point marken on the line T3-T4 is that point. (Note - the red point shudve been on the wire (T3-T4), it didnt come up in the image, sry abt that)

Okay, so at that point, the magnetic field is pointing in the direction of the blue arrow (consider it as a tangent to the circle)

The brown arro indicates the current.

If u arrange ur left hand in this form u will see the movement of the wire is towards the thick rigid wire as ur thumb points towards it.

im not sure abt this, astar plz check. thanks

Dude, that was an A 1 explanation. Short and sweet, the way I like it. Thanks alot understood it completely . I'd +rep you but I have to spread the love  :D
Title: Re: Chemistry, Physics
Post by: Ghost Of Highbury on May 05, 2010, 09:56:26 am
Thanks, dont worry abt the rep. Dude, one confusing thing here.

As  both the wires are conducting current, both will have their magnetic field, thus u may ask, y is the magnetic field of the thicker wire taken into consideration. I think this is because the thicker wire will have less resistance, and thus more current which makes the magnetic field stronger.
Title: Re: Chemistry, Physics
Post by: The Golden Girl =D on May 05, 2010, 09:58:43 am
i didn't get the blue aroow thing :(
Title: Re: Chemistry, Physics
Post by: Ghost Of Highbury on May 05, 2010, 10:03:18 am
its the direction of the magnetic field at THAT POINT . the reason i stress on the point is because the magnetic field is circular and the blue line is the tangent to that circle.
Title: Re: Chemistry, Physics
Post by: The Golden Girl =D on May 05, 2010, 10:08:21 am
@A@di - i understood the question finally ..lol :D thx!!!!
Title: Re: Chemistry, Physics
Post by: gaurav95 on May 06, 2010, 05:10:06 am
its the direction of the magnetic field at THAT POINT . the reason i stress on the point is because the magnetic field is circular and the blue line is the tangent to that circle.

Thanks for all your explanations
I'd + rep for that
In the q above how did u determine the direction of magnetic field???????????
but as a i said can u give more e.g.s thx                 
Title: Re: Chemistry, Physics
Post by: holtadit on May 06, 2010, 11:47:13 am
Thanks for all your explanations
I'd + rep for that
In the q above how did u determine the direction of magnetic field???????????
but as a i said can u give more e.g.s thx                 

The mag field always flows from North pole to South pole, so your index finger points from North towards the south pole.
Title: Re: Chemistry, Physics
Post by: gaurav95 on May 06, 2010, 01:18:25 pm
The mag field always flows from North pole to South pole, so your index finger points from North towards the south pole.

I know that but where are the S and North poles and Examples pls
Title: Re: Chemistry, Physics
Post by: holtadit on May 07, 2010, 04:19:03 pm
I know that but where are the S and North poles and Examples pls

They will be shown
Title: Re: Chemistry, Physics
Post by: Dibss on May 09, 2010, 12:31:02 pm
Quote
The orange line indicates the magnetic field. As u can see it is in a circular form, Now, here u have to use the flemming's left hand rule.

However, as the magnetic field is in circular form u have to choose one point to apply the Left hand rule. The red point marken on the line T3-T4 is that point. (Note - the red point shudve been on the wire (T3-T4), it didnt come up in the image, sry abt that)

Okay, so at that point, the magnetic field is pointing in the direction of the blue arrow (consider it as a tangent to the circle)

The brown arro indicates the current.

If u arrange ur left hand in this form u will see the movement of the wire is towards the thick rigid wire as ur thumb points towards it.

hey A@di, is this by any chance the solution for m/j 08 q9? Are you sure that's the answer because i think i recognize the question and i distinctly remember my teacher giving me a completely different explanation and mentioning that it was a different concept... should i elaborate?
Title: Re: Chemistry, Physics
Post by: holtadit on May 09, 2010, 12:41:24 pm
hey A@di, is this by any chance the solution for m/j 08 q9? Are you sure that's the answer because i think i recognize the question and i distinctly remember my teacher giving me a completely different explanation and mentioning that it was a different concept... should i elaborate?

Please do.
Title: Re: Chemistry, Physics
Post by: soualhi1 on May 09, 2010, 01:20:54 pm
@A@di: how do we know where to place our hand?

Cos I did the mistake of the force finger coming out of the page, but the current finger is the same, so which way do we know how to place our hand ??? ???
Title: Re: Chemistry, Physics
Post by: Dibss on May 09, 2010, 01:33:46 pm
ok i'm attaching a picture of the notes my teacher made me jot down at the end of the question. When 2 parallel wires carry current tin the same direction the effect of the combined magnetic field results in a force of attraction. if directions are different --> force of repulsion. 9c) says there's a current going down both wires. the attachment shows combined field causing both wires to be attracted to each other. since thick rigid wire can't move, the flexible wire ends up moving toward thick wire T1-T2.
Title: Re: Chemistry, Physics
Post by: holtadit on May 09, 2010, 02:29:50 pm
ok i'm attaching a picture of the notes my teacher made me jot down at the end of the question. When 2 parallel wires carry current tin the same direction the effect of the combined magnetic field results in a force of attraction. if directions are different --> force of repulsion. 9c) says there's a current going down both wires. the attachment shows combined field causing both wires to be attracted to each other. since thick rigid wire can't move, the flexible wire ends up moving toward thick wire T1-T2.

Look at the picture. As the current is travelling downwards there is a south pole induced on both.


Wouldnt that cause repulsion ?
Title: Re: Chemistry, Physics
Post by: Dibss on May 09, 2010, 02:52:56 pm
@ari
hope the diagram helps...
although i'm not really an expert at explaining and could be making a mistake :/ could someone check this?
Title: Re: Chemistry, Physics
Post by: Ghost Of Highbury on May 09, 2010, 03:05:09 pm
Look at the picture. As the current is travelling downwards there is a south pole induced on both.


Wouldnt that cause repulsion ?

yes, i think so too. astar can check it.
Title: Re: Chemistry, Physics
Post by: Dibss on May 09, 2010, 03:08:51 pm
Quote
yes, i think so too.
yikess :-\
Quote
astar can check it.
ok:]
Title: Re: Chemistry, Physics
Post by: Fastal on May 09, 2010, 06:06:06 pm
is this right?
Title: Re: Chemistry, Physics
Post by: astarmathsandphysics on May 09, 2010, 07:31:55 pm
no this is
Title: Re: Chemistry, Physics
Post by: $H00t!N& $t@r on May 09, 2010, 10:06:21 pm
ok i'm attaching a picture of the notes my teacher made me jot down at the end of the question. When 2 parallel wires carry current tin the same direction the effect of the combined magnetic field results in a force of attraction. if directions are different --> force of repulsion. 9c) says there's a current going down both wires. the attachment shows combined field causing both wires to be attracted to each other. since thick rigid wire can't move, the flexible wire ends up moving toward thick wire T1-T2.


You answer is right. That's exactly what my teacher taught me!  8)
Title: Re: Chemistry, Physics
Post by: Dibss on May 10, 2010, 02:55:40 pm
phew :)
Title: Re: Chemistry, Physics
Post by: WARRIOR on May 12, 2010, 06:13:48 pm
if u still care..how my teacher tought me is

the effect is opposite to that of magnets for example

If both wires have current going downswards ( pretens its like magnets ) so north and north they are supposed to repel..but no in this case its the oposite they attract

if wires have current in opsite diretecttion..so north and south..they suposed to attract but no in this case its the opsoite they repel

cheers good revision for me :p