IS queation!!!!! 30分

1) Electrons are negatively charged. When they are free to move, they are attracted towards the positively charged protons by electrostatic attraction.

2) 會。 V = IR, V is Voltage, I is current, R is resistance. If current unchanges, the larger the resistance, the larger the voltage. That means, a light bulb of a larger resistance, it gets more energy than a light bulb of smaller resistance.

3) 因為 wire in the fuse melts under high temperature and breaks the circuit.

4) There are different types of dry cells.
Zinc- carbon cell:
The container of the dry cell, which also serves as one of the electrodes, is made of zinc. The container is lined with porous paper bag which separates the metal from the materials within the cell. A carbon (graphite) rod is placed at the center and used as the other electrode. The space between the carbon rod and the zinc container is filled with a moist mixture of ammonium chloride, manganese dioxide, zinc chloride and carbon powder.
http://en.wikipedia.org/wiki/Image:Zincbattery.png

Alkaline batteries are a type of power cell dependent upon the reaction between zinc(-) and manganese(IV) dioxide (Zn/MnO2) (+)

Silver-oxide battery are available in either very small sizes as button cells
A silver oxide battery is a small-sized primary battery using zinc as the negative electrode (anode), silver oxide as the positive electrode (cathode) plus an alkaline electrolyte, usually sodium (NaOH) or potasium hydroxide (KOH).

The nickel-cadmium battery (commonly abbreviated NiCd) contain a nickel hydroxide positive electrode plate, a cadmium hydroxide negative electrode plate, a separator, and an alkaline electrolyte. NiCd batteries usually have a metal case with a sealing plate equipped with a self-sealing safety valve. The positive and negative electrode plates, isolated from each other by the separator, are rolled in a spiral shape inside the case.


5) A short circuit is an accidental low-resistance connection between two nodes of an electrical circuit that are meant to be at different voltages. This results in an excessive electric current and potentially causes circuit damage, overheating, fire or explosion.

e.g. A short circuit is to connect the positive and negative terminals of a battery together with a low-resistance conductor, like a wire. With low resistance in the connection, a high current flows, causing the cell to deliver a large amount of energy in a short time.


Voltages across components in parallel circuit with each other are the same in magnitude and they also have identical polarities.


That means, V in different parts of a short circuit are different and result in overheating in some parts; while V in any parts of a // circuit are always the same.

1.electrons attraction
2.ys
3.fuse melts when it meets with high temperature
4.positive and negative sides some liquid inside to maintain the flow of electrons
5.short circuit:cells and wire :square
并聯:日字型