How does the heating element of a portable electric heater work

The heating element of an electric heater works following the Joule's effect. In fact, the main component of the heating element is a resistor. When the heater is connected to the plug, electrical current starts flowing through the resistor. Because of the Joule's effect, the temperature of the resistor increases: therefore, the resistor gets hotter and releases heat to the surroundings.

the answer is neither ball has a charge.

because if they were both positively charged, they will repel each other.

if they were positively and negatively charged, they will seek.

the box does not move because you need to use a force greater than 300 n. you are only using 50 n. it needs to at least be 301 n for the box to move because then it is an unbalanced force and it will move the way that the greater force is pushing it. if you use only 300 n it will be a balanced force and will not move because the force you are exerting on the   box is the same as its force.

hope this !

im sorry if i went too in depth, i am going to include a link to a video on khan academy that will explain this.   hope that you like the video and that it explains more in detail to you.

that is the link.