Physics Question

[bloop]

HI,

I need help, answer is B.

[blasonduo]

Hello!

Okay, I may have something wrong here, so hopefully someone can check, but i'm pretty sure

The first step is to figure out the direction of the magnetic field (either left to right of right to left)

From the positive terminal you can see that the magnets are going to be ELECTROMAGNETS, you can see that it wraps around the LEFT block in clockwise way, You know it has a SOUTH facing pole (I use Nanti-Socks to remember )

To double check, we'll do the other side, from the NEGATIVE terminal, this time, it is travelling in an ANTI-clockwise way (remember to look at it standing in the middle) This means that the RIGHT block is the NORTH pole. So the magnetic field lines follow from RIGHT to LEFT.

The next part is the simple right hand palm rule, as you know the + and - terminals, follow the current lines until the right option works. In this case, B is the only one that rotates clockwise. (Left side coil current goes up (so thumb up!) and magnetic field right to left (so fingers to right) shows the palm upwards and thus it rotating clockwise.

Basically, this question is asking about your ability to figure out electromagnets, As B and D are almost the same, where D's RIGHT block is coiled the wrong way!

Thanks

[JeffChiang]

From the positive terminal you can see that the magnets are going to be ELECTROMAGNETS, you can see that it wraps around the LEFT block in clockwise way, You know it has a SOUTH facing pole (I use Nanti-Socks to remember )

How do you figure this out?

[blasonduo]

How do you figure this out?

Just follow the Positive terminal's wire, In B, when it reaches the block, it goes straight up (indicating a clockwise coil) If you follow the negative terminal, you can see it goes UNDER the block and hence is going the other way (anti-clockwise)

If you are asking how I know its an electromagnet, it's because there is current flowing through the coils, and thus will produce a magnetic field.

[JeffChiang]

Just follow the Positive terminal's wire, In B, when it reaches the block, it goes straight up (indicating a clockwise coil) If you follow the negative terminal, you can see it goes UNDER the block and hence is going the other way (anti-clockwise)

If you are asking how I know its an electromagnet, it's because there is current flowing through the coils, and thus will produce a magnetic field.

Sorry, blasonduo. I was wondering how does the clockwise or anti-clockwise wire make it north or south? Which rule is this?

[kiwiberry]

Sorry, blasonduo. I was wondering how does the clockwise or anti-clockwise wire make it north or south? Which rule is this?

Using the right hand grip rule- fingers in the direction of the current, thumb will face the direction of the field!

[JeffChiang]

Using the right hand grip rule- fingers in the direction of the current, thumb will face the direction of the field!

OMG! I can't believe it! I forgot that right hand grip rule can be reversed so fingers is I and thumb is B. Thanks both of you!

[blasonduo]

Goodluck with your studies