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#1
which wing tip will become positive? huh? pleaaseee help, these questions are getting more and more ridiculous
I was thinking LH rule so motion is towards east, then perpendicular component of field is facing north, which means "current" is into the page, but the answer is where X I crossed.
0
2 years ago
#2
The airplane wings collectively form the stick, while the airplane body is the other stick that rubs on the magnetic field in parallel.
Use the stick (or airplane wings) to cut through the magnetic field lines of the earth. Remember, cutting requires power, so there has to be potential on the stick that could be modelled with your right hand. Your thumb will point in the direction of motion, while your hand is the stick. The bottom of your hand is the high potential, and the energy flooooows through to the top of your hand.

I'm saying stick because we're usually given a metal stick cutting through a magnetic field in the typical problems.

Seriously. This is easier to remember than Faraday's law of induction and the accompanying Lenz's law.
1
#3
(Original post by diwangislucky)
The airplane wings collectively form the stick, while the airplane body is the other stick that rubs on the magnetic field in parallel.
Use the stick (or airplane wings) to cut through the magnetic field lines of the earth. Remember, cutting requires power, so there has to be potential on the stick that could be modelled with your right hand. Your thumb will point in the direction of motion, while your hand is the stick. The bottom of your hand is the high potential, and the energy flooooows through to the top of your hand.

I'm saying stick because we're usually given a metal stick cutting through a magnetic field in the typical problems.

Seriously. This is easier to remember than Faraday's law of induction and the accompanying Lenz's law.
thank you very much for your help! I'm sorry I don't get it (im crap at physics, I know haha),
Thanks a lot though i appreciate it
0
2 years ago
#4
(Original post by sarah99630)
thank you very much for your help! I'm sorry I don't get it (im crap at physics, I know haha),
Thanks a lot though i appreciate it
(Original post by diwangislucky)
The airplane wings collectively form the stick, while the airplane body is the other stick that rubs on the magnetic field in parallel.
Use the stick (or airplane wings) to cut through the magnetic field lines of the earth. Remember, cutting requires power, so there has to be potential on the stick that could be modelled with your right hand. Your thumb will point in the direction of motion, while your hand is the stick. The bottom of your hand is the high potential, and the energy flooooows through to the top of your hand.

I'm saying stick because we're usually given a metal stick cutting through a magnetic field in the typical problems.

Seriously. This is easier to remember than Faraday's law of induction and the accompanying Lenz's law.

diwangislucky (previous poster) is partially correct (Right Hand Rule), but I have no idea what he/she is saying about sticks and hands. My strongest advice: you will get yourself into a whole heap of mess unless you correctly apply the laws and conventions laid down by Faraday and Lenz. Especially if the question requires an explanation. Doing your 'own thing' will lose marks for any description which does not correctly apply the rules.

OK, as with everything in Physics, the first task is to work out which rules to apply:

1) The question tells us the wing tips become charged, which means a potential difference is developed across the wing span.

Electrons must therefore flow (current) from one wing tip to the other and, as a result, a net +ve charge builds up on one wing tip and a net -ve charge on the other tip as the wings cut the lines of the earths magnetic flux.

i.e. the previous poster correctly points out that the wing span describes a length of conductor, cutting the earths magnetic flux in the direction of flight which is out of the page in the diagram, and an induced current flows across the wingspan bunching a difference of charge at the wing tips.

2) Motion (applied force) through a magnetic field causes a current, and is the description of a generator (dynamo) so Flemings Right Hand Rule must apply. The Left Hand Rule applies to motors (current in a conductor moving through a magnetic field causes motion)

3) Right Hand Rule:

So we need to orientate the right hand by using the thumb (motion) and forefinfer (field) to work out the direction of current (I) flow (mIddle finger).

There are two things that can trip us up:

a) The first is the direction of the magnetic field which is defined as from magnetic north to magnetic south. NB The earths' magnetic north is at the geographic south pole, and the earths' magnetic south pole is at the geographic north pole. So the lines of flux in the diagram are in the magnetic direction from the top of the page (north magnetic pole) to the bottom of the page (south magnetic pole).

The forefinger of the right hand (field) therefore needs to point from the top of the page to the bottom of the page.

The thumb must point in the direction of motion of the aircraft i.e. out of the page.

This means the direction of conventional current flow is from the left wing tip to the right wing tip.

b) The second thing that can trip us up is making sure we understand that Flemings rules describe conventional current which is in the opposite direction to actual charge flow

In other words, the actual charge (electrons) flow from the right hand wing tip to the left hand wing tip.

4) Finally, electrons (-ve charge carriers) flowing from the right hand wing tip produce a net +ve charge on the right hand wing tip and build up of -ve charge on the left hand wing tip.

The RIGHT HAND WING TIP is therefore POSITIVE

0
2 years ago
#5
(Original post by uberteknik)
diwangislucky (previous poster) is only partially correct (Right Hand Rule), but I have no idea what he/she is saying about sticks and hands. My strongest advice: you will get yourself into a whole heap of mess unless you correctly apply the laws and conventions laid down by Faraday and Lenz. Especially if the question requires an explanation. Doing your 'own thing' will lose marks for any description which does not correctly apply the rules.

OK, as with everything in Physics, the first task is to work out which rules to apply:

1) The question tells us the wing tips become charged, which means a potential difference is developed across the wing span.

Electrons must therefore flow (current) from one wing tip to the other and, as a result, a net +ve charge builds up on one wing tip and a net -ve charge on the other tip as the wings cut the lines of the earths magnetic flux.

i.e. the wing span is a length of conductor, cutting the earths magnetic flux in the direction of flight which is out of the page in the diagram, and an induced current flows across the wingspan bunching a difference of charge at the wing tips.

2) Motion (applied force) through a magnetic field causes a current, and is the description of a generator (dynamo) so Flemings Right Hand Rule must apply. The Left Hand Rule applies to motors (current in a conductor moving through a magnetic field causes motion)

3) Right Hand Rule:

4) So we need to orientate the right hand by using the thumb (motion) and forefinfer (field) to work out the direction of current (I) flow (mIddle finger).

There are two things that can trip us up:

a) The first is the direction of the magnetic field which is defined as from magnetic north to magnetic south. NB The earths' magnetic north is at the geographic south pole, and the earths' magnetic south pole is at the geographic north pole. So the lines of flux in the diagram are in the magnetic direction from the top of the page (north magnetic pole) to the bottom of the page (south magnetic pole).

The index finger of the right hand (field) therefore needs to point from the top of the page to the bottom of the page.

The thumb must point in the direction of motion of the aircraft i.e. out of the page.

This means the direction of conventional current flow is from the left wing tip to the right wing tip.

b) The second thing that can trip us up is making sure we understand the Flemings rules describe conventional current which is in the opposite direction to actual charge flow

In other words, the actual charge (electrons) flows from the right hand wing tip to the left hand wing tip.

5) Electrons flow from the right hand wing tip producing a net +ve charge on the right hand wing tip and build up of -ve charge on the left hand wing tip.

The RIGHT HAND WING TIP is therefore POSITIVE

I usually use Lenz’s law on an imaginary stationary circuit of infinite resistance for these types of problems. Hmmm thanks for the long answer tho.
1
#6
(Original post by uberteknik)
diwangislucky (previous poster) is partially correct (Right Hand Rule), but I have no idea what he/she is saying about sticks and hands. My strongest advice: you will get yourself into a whole heap of mess unless you correctly apply the laws and conventions laid down by Faraday and Lenz. Especially if the question requires an explanation. Doing your 'own thing' will lose marks for any description which does not correctly apply the rules.

OK, as with everything in Physics, the first task is to work out which rules to apply:

1) The question tells us the wing tips become charged, which means a potential difference is developed across the wing span.

Electrons must therefore flow (current) from one wing tip to the other and, as a result, a net +ve charge builds up on one wing tip and a net -ve charge on the other tip as the wings cut the lines of the earths magnetic flux.

i.e. the previous poster correctly points out that the wing span describes a length of conductor, cutting the earths magnetic flux in the direction of flight which is out of the page in the diagram, and an induced current flows across the wingspan bunching a difference of charge at the wing tips.

2) Motion (applied force) through a magnetic field causes a current, and is the description of a generator (dynamo) so Flemings Right Hand Rule must apply. The Left Hand Rule applies to motors (current in a conductor moving through a magnetic field causes motion)

3) Right Hand Rule:

So we need to orientate the right hand by using the thumb (motion) and forefinfer (field) to work out the direction of current (I) flow (mIddle finger).

There are two things that can trip us up:

a) The first is the direction of the magnetic field which is defined as from magnetic north to magnetic south. NB The earths' magnetic north is at the geographic south pole, and the earths' magnetic south pole is at the geographic north pole. So the lines of flux in the diagram are in the magnetic direction from the top of the page (north magnetic pole) to the bottom of the page (south magnetic pole).

The index finger of the right hand (field) therefore needs to point from the top of the page to the bottom of the page.

The thumb must point in the direction of motion of the aircraft i.e. out of the page.

This means the direction of conventional current flow is from the left wing tip to the right wing tip.

b) The second thing that can trip us up is making sure we understand that Flemings rules describe conventional current which is in the opposite direction to actual charge flow

In other words, the actual charge (electrons) flow from the right hand wing tip to the left hand wing tip.

4) Finally, electrons flowing from the right hand wing tip produce a net +ve charge on the right hand wing tip and build up of -ve charge on the left hand wing tip.

The RIGHT HAND WING TIP is therefore POSITIVE

Oh thank you SO so much. I always used LH rule for EVERYTHING! Well now I know. Not all heroes wear capes
0
2 years ago
#7
(Original post by sarah99630)
Oh thank you SO so much. I always used LH rule for EVERYTHING! Well now I know. Not all heroes wear capes
0
#8
Hi! uberteknik
why is right hand rule being used for part (b)? Not left? Thanks in advance.
0
2 years ago
#9
(Original post by sarah99630)
...
why is right hand rule being used for part (b)? Not left? Thanks in advance.
You should be using Fleming Left-hand rule to determine the direction of magnetic field.

http://physicsnotes.awardspace.co.uk...hand_rule.html
1
#10
(Original post by Eimmanuel)
You should be using Fleming Left-hand rule to determine the direction of magnetic field.

http://physicsnotes.awardspace.co.uk...hand_rule.html
Thank you! I did use LHR and so I got field INTO the page,because current is going south, and motion is to the right... but the answer is field is out of the page.
0
2 years ago
#11
(Original post by sarah99630)
Thank you! I did use LHR and so I got field INTO the page,because current is going south, and motion is to the right... but the answer is field is out of the page.
https://revisionscience.com/sites/re...c_20150812.pdf

Arrow added to diagram downwards on or near the copper rod
An indication that the field is at right angles to the page or copper rod
Magnetic field into page
0
#12
(Original post by Eimmanuel)
https://revisionscience.com/sites/re...c_20150812.pdf

Arrow added to diagram downwards on or near the copper rod
An indication that the field is at right angles to the page or copper rod
Magnetic field into page
sorryyyy my bad! That's a relief! Thank you so much, lifesaver.
0
2 years ago
#13
(Original post by sarah99630)
Thank you! I did use LHR and so I got field INTO the page,because current is going south, and motion is to the right... but the answer is field is out of the page.
Your reasoning is correct. Use LHR, current flow top to bottom (middle finger), force to the right (thumb), field indicated by index finger INTO page.

Emmanuel posted mark scheme for Q11.
1
#14
(Original post by uberteknik)
Your reasoning is correct. Use LHR, current flow top to bottom (middle finger), force to the right (thumb), field indicated by index finger INTO page.

Emmanuel posted mark scheme for Q11.
thank you very much! Sorry, my bad! exam adrenaline rush I guess
0
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