This chapter explores the ways in which devices can be connected in electrical circuits. All electrical devices can be connected in series or parallel. A device is said to be in a series circuit when all current traveles throught each resistor. Parallel circuits, on the other hand, have several current paths.The circuit contains a voltage source and three resistors, the current flows through three paths in the parallel circuit. An important application of the series resistors is the voltage divider, the voltage divider supplies the desired voltage.
Also, in the series circuit the equivalent resistance is larger than any single resistance. However , in parallel circuits the equivalent resistance can be replaced by a single resistor. The equivalent resistance of the circuit is decreased when placing a resistor in parallel with an existing resistor.
This little diagram is an example of a series circuit. Such diagrams are called schematics, but anyway, in this picture the wavy lines represent the lamps or resistors, the bold circle is the ampmeter, and the bold circle with two lines at its side is the power source or generator.
Equivalent resistance, for resistors in series, is the sum of all the resistances, R= R1+R2+R3. That is why the equivalent resistance is larger than any single one. The current is calculated by using the following equation, I= V/R. I is the current, V is the magnitude, and R is the resistance. But in a parallel circuit its equivalent resistance is found by using this equation, 1/R= 1/R1+1/R2+1/R3.
In an electic circuit, fuses and circuit breakers are switches that act as safty devices, just in case it overloads or there's a short circuit, so the object won't be a hazard. An overload can occur when too many appliances are conected at the same time and a short circuit occurs when a circuit is formed tat has a very low resistance. A fuse is a short piece of metal that melts from the heating effect of the passing current. A ground-fault interupter prevents dangerious shocks by detecting small differences or changes in current, mostly caused by the extra current path and opens the circuit.
Here are two devices that measure current, they are ammeter and voltmeter. An ammeter measures the current in any part of a circuit. To use it you would have to place it in series with the resistance. A voltmeter is used to measure the voltage drop across any part of a circuit.
References:
Book- Merril, Physics---Principals and problems--- Published by: Macmillan/ McGraw-Hill Year:1992, 1990Magazine Articles: scientific american
a better pohtovoltaic cell.