Polarity of Hall Voltage

Hi everyone!

I don't understand why using positive rather than negative charge carriers does not reverse the polarity of the Hall voltage.

(iii) State and explain the effect, if any, on the polarity of the Hall voltage when negative charge carriers (electrons) are replaced with positive charge carriers, moving in the same direction towards the slice.

Mark scheme:
negative and positive charge (carriers) would deflect in opposite directions (okay, get that)
so no change in polarity (what???)

Please help.
Thanks!

Reply 1

uberteknik

21

-ve mobile charge carriers build on one side of the slice under the influence of the magnetic field (creating a net -ve surplus) charge and deplete the other side leaving a net +ve charge on that side. A polarised electric field is thus created across the slice.

Using the same convention under the influence of the same magnetic field:

+ve mobile charge carriers would move in the opposite direction to the above.

i.e. the result is that the +ve and -ve charges still build up on the same sides as above. The electric field is the same direction in both instances.

OP

Aaah! Thank you!

But currwnt will deflect on a different side of the plate by fleming left hand rule howw

Original post by Gohgene

But current will deflect on a different side of the plate by fleming left hand rule how

Let say we apply Fleming’s left hand rule (FLHR) the situation posted by OP. The negative charge (or electrons) is deflected to the plane QRXW, so the side QRXW is negatively charged and the side PSYV is positively charged.

Next, the electron current is replaced by a positive charge current that is in the same direction towards the slice. When we apply FLHR, the positive charge is deflected to plane PSYV, so the side PSYV is positively charged again with side QRXW negatively charged.

When we apply FLHR to electron flow, we need to be careful as FLHR is applied for conventional current.
But you can change Fleming’s left hand to right hand for electron flow to deduce the deflection of the electron. The result does not change.

Reply 5

Gohgene

2

Doesnt the direction of current changes when the current flows into the devide at the same direction , as current opposes movement of electron and it is same direction as the movement of positive charge

Original post by Gohgene

Doesnt the direction of current changes when the current flows into the devide at the same direction , as current opposes movement of electron and it is same direction as the movement of positive charge

Not really sure what are you describing.

What do you mean by saying current opposes movement of electrons?

Reply 7

Gohgene

2

I mean ,wont the electrons deflect towards ps when electrons is replaced with positive charge due to FLHR

Original post by Gohgene

I mean ,wont the electrons deflect towards ps when electrons is replaced with positive charge due to FLHR

It seems that you are not applying FLHR correctly for the flow of positive charges.
I mention that the positive charge is deflected to plane PSYV if you apply FLHR.

Original post by Gohgene

Doesnt the direction of current changes when the current flows into the devide at the same direction , as current opposes movement of electron and it is same direction as the movement of positive charge

Original post by Gohgene

I mean ,wont the electrons deflect towards ps when electrons is replaced with positive charge due to FLHR

The diagram illustrates what I describe in post #5.

Reply 10

Gohgene

2

Thank you for the clarification , appreciated 😇

Original post by Gohgene

Thank you for the clarification, appreciated 😇

Reply 12

lil_dev1998

1

Original post by Geometrica

Hi everyone!

I don't understand why using positive rather than negative charge carriers does not reverse the polarity of the Hall voltage.

(iii) State and explain the effect, if any, on the polarity of the Hall voltage when negative charge carriers (electrons) are replaced with positive charge carriers, moving in the same direction towards the slice.

Mark scheme:
negative and positive charge (carriers) would deflect in opposite directions (okay, get that)
so no change in polarity (what???)

Please help.
Thanks!

just solved that question still confused like you bro

Polarity of Hall Voltage

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