1) Explain whether a solenoid will attract paper clips if here is no current thr

Question

1) Explain whether a solenoid will attract paper clips if here is no current through its coils. Predict what will happen to the force between the solenoid and the paper clips if you increase the current in the coils or increased the number of turns of coil per unit length? Explain

2) A student comments: "If we change the direction of the current in the solenoid coils from say, clockwise to counterclockwise, the paper clips will be attracted by the solenoid in one case and repelled in the other." Explain why you agree or disagree

3) A student comments: "if we bring the north pole of a bar magnet close to one end of a current carrying solenoid and the bar magnet and the solenoid attract, then if I bring the south pole of the bar magnet close to the same end of the solenoid, the two will repel. This is because the solenoid is also a magnetic dipole (magnet) with north poles and sound poles at the two ends." explain why you agree or disagree

4) A student comments: "If we bring together the ends of two current carrying solenoids and they attract, then if we flipped the end of only one of the solenoids, the two solenoids will repel." Explain why you agree or disagree

5) A student comments: "If we bring together the ends of two solenoids with different currents flowing through them, the one with larger current through its coils will exert a greater force on the solenoid carrying the smaller current" Explain why you agree or disagree.

Explanation / Answer

a)as current =0 ...thus there is no magnetic force...hence there will be no force attracting the paper clips

B=(mu)*N*I/L ...thus as N or I increases ....magnetic field strehgth increases..hence force increases....

b) yes...they will be repelled as the direction of the magnetic field is reversed...hence force acts upon the opposite direction ...thus repelling the clips...

c)yes..it is true.....since the solenoid clearly shows south-pole character in that side...as it attracts the north pole side of the bar magnet....we note that the magnetic flux lines move from the north pole to the south....hence the flux lines are clearly moving into the solenoid at the side...hence repelling the south pole of the bar magnet

d)yes ..it is true....as the magnetic fields produced by each of them repels....ie if one side of the solenoid acted (before flipping) as the north...this time(after flipping) it acts as the south....hence reversing poles....thus repeling the other solenoid

e)no...as force depends on both the currents flowing in the respective solenoids.....and also since newton's third law states that action and reaction forces are the same...so..forces exerted on each other are the same....but not the magnetic fields

if you still have doubts ...i'll be happy to clear them up

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