Why couldn't nawaz hear the bell when the air had been pumped out of the jar?

1.) Attractive and repulsive properties of the magnetic poles

2.) The magnetic force of the object 1 cm away will be 36 times stronger than the magnetic force of the object that is 6 cm away.

Explanation:

1.) Magnetic Levitation vehicles don't require engine neither do they consume fuel. They are high speed vehicles that are lifted by magnetic repulsion, and propagate along an elevated guideway by strong powerful magnets attached to the vehicle without no physical contact with the guideway.

Maglev vehicles are raised off the track when it levitates by magnetic attraction, in which levitation  magnets on the underside of the guideway attract the opposite poles of magnets on the wrap around section of the  maglev.

2.) Magnetic force obeys an inverse square law with distance.

The magnetic force of the object 1 cm away will be 36 times stronger than the magnetic force of the object that is 6 cm away. Because the magnetic force is inversely proportional to the square of the distance.