chemical and solar cells
Chemical cells are found in batteries. They produce voltage by means of chemical reactions. Chemical cells have two electrodes, which are strips of different materials, such as zinc and carbon. The electrodes are suspended in an electrolyte. This is a substance that contains free ions, which can carry electric current. The electrolyte may be either a paste, in which case the cell is called a dry cell, or a liquid, in which case the cell is called a wet cell. Flashlight batteries contain dry cells. Car batteries contain wet cells. The Figure 1.1 shows how a battery works. The diagram represents the simplest type of battery, one that contains a single chemical cell. Both dry and wet cells work the same basic way. The electrodes react chemically with the electrolyte, causing one electrode to give up electrons and the other electrode to accept electrons. Electrons flow through the electrolyte from the negative to positive electrode. The electrodes extend out of the battery for the attachment of wires that carry the current. The current can be used to power a light bulb or other electric device.
Solar cells convert the energy in sunlight to electrical energy. Solar cells are also called photovoltaic (PV) cells because they use light (photo-) to produce voltage (-voltaic). Solar cells contain a material such as silicon that absorbs light energy. The energy knocks electrons loose so they can flow freely and produce a difference in electric potential energy, or voltage. The flow of electrons creates electric current. Solar cells have positive and negative contacts, like the terminals in chemical cells. If the contacts are connected with wire, current flows from the negative to positive contact. The Figure 1.2 shows how a solar cell works.
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electric current requires a source of voltage.
--> a. true b. false
solar cells are found in batteries.
a. true --> b. false
the source of voltage in a battery comes from
--> a) chemical reactions. b) solar energy. c) electric current. d) none of the above
a car battery is a dry cell.
a. true --> b. false
which statement about how a chemical cell works is false?
a) the electrodes react chemically with the electrolyte. --> b) both electrodes give up electrons. c) electrons flow through the electrolyte. d) one electrode is negative and one is positive.
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