A long wire that carries a current is bent into a solenoid with upward current in the front looking. If the observer could "see" the magnetic field inside this arrangement of solenoid from the right side, how would it appear?
a) The observer would "see" a north pole
b) The observer would "see" a south pole
c) The observer would "see" an upward north pole
d) The observer would "see" a downward north pole
The observer would "see" a south pole. In a solenoid, the magnetic field lines form concentric circles around the wire. The direction of the magnetic field inside the solenoid can be determined using the right-hand rule: if you curl your right-hand fingers in the direction of the current, your thumb will point in the direction of the magnetic field. In this case, with upward current in the front looking, the magnetic field lines inside the solenoid would be pointing in a clockwise direction when viewed from the right side. According to magnetic field convention, this direction corresponds to a south pole. Therefore, the observer would "see" a south pole.
So, the correct answer is b) The observer would "see" a south pole.
To determine how the magnetic field would appear inside the solenoid, we can use the right-hand rule for the magnetic field. The right-hand rule states that if you imagine gripping the wire of the solenoid with your right hand, such that your thumb indicates the direction of the current flow, your fingers would curl in the direction of the magnetic field lines.
In this case, the solenoid has upward current in the front looking. So, if you imagine holding the solenoid wire in your right hand and pointing your thumb upwards (since the current is upward), your fingers will curl in the clockwise direction. This means that the magnetic field lines inside the solenoid will circulate clockwise when viewed from the right side of the solenoid.
As for the poles, the magnetic field lines appear in a direction from the south pole to the north pole. Since the magnetic field lines inside the solenoid are circulating clockwise from the right side, when viewing from the right side, the observer would "see" a north pole.
Therefore, the correct answer is:
a) The observer would "see" a north pole.
"upward current in the front looking" ?
Just take your right hand, wrap it aound the wire, thumb in the direction of + current flow, B will be in the direction of the fingers.