Investigations 3 and 4 Review

Investigation 3 I can build a series circuit and explain how the electricity flows through it. I can build a parallel circuit and explain how the electricity flows through it. I can compare series and parallel circuits and explain the advantages of each. I can read and create schematic diagrams of series and parallel circuits.

Investigation 4 I can build an electromagnet. I can describe how the number of winds of wire around a core affects the strength of an electromagnet. I can change the strength of an electromagnet in various ways.

Series Circuits A series circuit has only ONE pathway for current to flow.

B ATTERY O RIENTATION Multiple D-cells in a series must be placed negative to positive for the current to flow through the circuit.

Examples of Parallel Circuits Parallel circuits split into two or more pathways before coming together at the D-cell.

Can you tell which circuit is a parallel and which is a series? The one on the left is a series circuit, as there is only ONE pathway for the current.

In a series circuit, both components are connected in a row, with electricity passing first through one then the other. In a parallel circuit, electricity passes through both components at the same time. Which is better for a string of lights?

A major advantage of parallel circuits is that if one component malfunctions, the other continues to function. (See bottom right.) In a series circuit, when one component breaks, both components stop working. (See bottom left.)

Electromagnets Using the electrical field produced from a battery, it is possible to create a temporary magnet. Because electric currents induce magnetic fields, wrapping a coil of wire around an object such as a nail or rivet and connecting it to a battery can create a magnet. The benefit of this type of magnet is that it can be turned on and off when it is needed.

Real Life Electromagnet This junkyard electromagnet can be turned on and off.

Components of an electromagnet: Steel rivet (steel core) Wire D-cell (power source) Switch (to turn it on/off)

Because electric current is running through the wire, if you have more coils of wire on the steel core, the electromagnet will be stronger. The relationship between winds of wire around a core and strength of force is: This electromagnet has only a few winds of wire and can only pick up only one metal shaving. More winds of wire= more strength Fewer winds of wire = less strength This electromagnet has many winds of wire and can pick up many metal shavings.

Time for a Quiz… 1. Series or Parallel: Which is which?

a) Parallel – more than one pathway to the D-cell b) Series – only one pathway to the D-cell

2. Which of these is NOT part of an electromagnet: A. Aluminum rivet B. D-cell C. Motor D. A and B E. A and C

E An aluminum rivet would not be useful because aluminum cannot be induced as a magnet. (The core of an electromagnet must be STEEL.) A motor is not needed to create an electromagnet. The electromagnet runs because of the energy from the D- cell.

3. What is the relationship between winds of wire around a core and strength of force of an electromagnet? A.Fewer winds of wire = less strength B.More winds of wire= more strength C.Both A and B D.Neither A nor B

C (A and B are correct) More winds give the electromagnet more strength, but fewer winds reduces the strength! This is a strong electromagnet. Look at all the winds!

Which D-cell orientation is correct? A. B.

A D-cells must be oriented negative to positive.

Which type of circuit is best for a string of lights? A. Parallel B. Series

A. Parallel In a parallel circuit, if one bulb goes out, the others will remain lit because each one has its own pathway to the power source. (That will make it much easier to find the broken bulb!) Good luck on your test!