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Question Is the magnetic field directed into the page or out of the page?

I am using this right hand rule --> RHR

So anyhow, my index finger is pointing downwards, and since the magnetic force is towards the right and this is an electron (negative) my thumb should point left.

But then my middle finger [the magnetic field] points towards the page. But the actual answer is that the magnetic field is coming out the page?

Where am I wrong?


closed as off-topic by David Z May 3 '16 at 18:43

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Since the electron is negatively charged, the index finger should point up. The force is to the right, so the thumb points to the right.

And then the middle finger comes out of the page.

You said you have your thumb pointing to the left because the electron is negatively charged. But in that case you should consider the current to be to the bottom of the page. You took the sign of the charge of the electron into account twice, and that's where you went wrong.

  • $\begingroup$ Thanks. Just one concern. Wasn't the rule "for an electron, the magnetic force is opposite to the direction of the thumb?" So if the magnetic force is towards the right according to the rule I should have made my thumb go left? The current/velocity should point down always right? $\endgroup$ – Amad27 May 3 '16 at 16:35
  • $\begingroup$ Thumb left ("force opposite") and index down makes the middle finger point out of the page. Or thumb right (direction of force) and index up (because charge negative) has the same effect. Pick one of the rules... not both. That's all. $\endgroup$ – Floris May 3 '16 at 17:02
  • $\begingroup$ Yes, I used the first one. But I don't see how you are using this. I did thumb left and index down and middle finger is pointing into the page? $\endgroup$ – Amad27 May 3 '16 at 17:17
  • 1
    $\begingroup$ You were using the wrong right hand, perhaps? $\endgroup$ – Floris May 3 '16 at 17:55
  • $\begingroup$ Should someone who is ambidextrous be making use of Fleming's rules? $\endgroup$ – jim May 3 '16 at 18:30

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