Day 15 Circuit Analysis

Today, we worked on understanding series and parallel circuits in DC

Morning Lab

Testing Bulb

Testing Battery

We spent the morning talking about which system, between series and paralllel has the brightest bulbs, and the brightest battery. The picture on the top shows that in series, the bulbs (represented by a schematics used for resistors) are the brightest, while in parallel, the batteries are shown to be the brightest, shown on the bottom picture. In order to maximize the brightness of the bulb, we need to maximize the amount of power delivered to the bulb, which is denoted by P=IV, power = the multitude of current and voltage.

Equation for power

Series Circuit and Parallel Circuit
This portion of the lab shows us how to use a multimeter to measure both voltages and currents in series and parallel circuits.

First portion of the lab (voltage in series)

This portion of the lab required us to understand the relationship between the voltage of the source and the voltage across the bulb, which shows that in series, they should be about equal to each other when added up

Recording current in series

In this portion of the lab, we find the relationship between currents all around, and we find out the current should be equal across the system in a series circuit

Voltage in parallel

In this portion of the lab, we find the voltages across the system should be about equal to each other across the parallel system

Current in Parallel

In this portion of the lab, we find that the current across the system should add up to be equal to the initial current in a parallel system








Resistance and its Measurementr

A cutaway view of a carbon resistor and its area

In this lab, we are going to oversee a few resistors, measure them based on their coloring code, and their acutal measurement, to see if they are within tolerable percent ranges

Resistors in question

Our resistors and coloring sequences

After looking at three different color sequences, and measuring for their resistances, we find that the percent difference yields less than 10%, making therm very valuable to buy.

More about Series and Resistors

Add caption

Taking from what we know from resistivity and adding it to equations for both series and parallel circuits, we can then find Resistance across both series and parallel circuits using length and area (along with the constant rho, that is found different within every metal)

Sample Problem answers

Kirchhoff's Law

Kirchhoff law states two thing

1)The sum of all the currents entering any node or branch point of a circuit (that is, where two or more wires merge)must equal the sum of all currents leaving the node.

2) Around any closed loop in a circuit, the sum of all emfs, voltage gains provided by batteries or other power sources, ( = emf) and all the potential drops across resistors and other circuit elements must equal zero.

By understanding these two laws, we can then understand how to solve for circuits that have more than one possible loop.

Sample problem involving Kirchhoff's Law

Answer to that problem 

It is to note that in this answer, the V50 and the V100 are the same, due to the fact that these system are parallel to each other