true or false
a small plastic ball has an excess negative charge on it. if a magnet is placed close to this ball, it will either attract or repel the ball, depending upon which pole is closer to the ball.
False. Excess charge generates an E (electric)field around the ball, but a B (magnetic) field is required to interact with a magnet. B fields are generated by currents or magnetic dipoles.
True.
When a small plastic ball has an excess negative charge, it means that it has an excess of electrons. Electrons carry negative charge. Now, if a magnet is placed close to the ball, it will experience a force due to the interaction between the magnetic field of the magnet and the charged particles (electrons) on the ball.
According to the principles of electromagnetism, opposite charges attract each other, while like charges repel each other. In this case, the small plastic ball will be attracted to or repelled by the magnet based on the polarity (pole) of the magnet.
If the pole of the magnet closer to the ball is a North pole, and since opposite charges attract, the excess negative charge (electrons) on the ball will be attracted towards the North pole of the magnet. Therefore, the ball will move towards the magnet.
On the other hand, if the pole of the magnet closer to the ball is a South pole, and since like charges repel, the excess negative charge (electrons) on the ball will be repelled by the South pole of the magnet. Therefore, the ball will move away from the magnet.
So, the closer pole of the magnet to the small plastic ball will determine whether the ball is attracted or repelled by the magnet.