Watch this video for an introduction to magnetism and electromagnetism: Show The second half of the video demonstrates how electrical current creates a magnetic field. Electrical current flows through a wire connected between the two terminals of a battery. However, the magnetic field around a single, straight piece of wire is fairly weak. You can make the magnetic field much stronger by wrapping the wire into a coil, also called a solenoid. As long as each turn of the coil goes in the same direction, the magnetic fields around each turn will add up, resulting in a stronger field. This is important; if two turns go in opposite directions, their fields will cancel out instead of adding up! You can make the field even stronger by wrapping the wire around a ferromagnetic core, like a nail. A solenoid with a ferromagnetic core is commonly called an electromagnet. Unlike a permanent magnet, an electromagnet can be turned on and off using electrical current. Many variables affect the strength of this electromagnet, and there are some variables that do not affect the strength. While the underlying physics are more advanced (see Additional Background section), middle school students can still do an experiment to identify the relationships between these variables and the strength of the electromagnet. Table 1 provides a summary of some variables and how they do or do not affect the strength of the magnet, but this list is not exhaustive. Figure 1 shows example data collected for the number of paper clips the magnet could lift vs. the number of turns in the coil (averages for three trials). Based on these data, adding more turns of wire makes the magnet stronger because it can lift more paper clips. Prep Work (5 minutes)Engage (5 minutes)Explore (40 minutes)Reflect (10 minutes)AssessMake Career ConnectionsLesson Plan Variations
Extracts from this document... Physics Lab Factors affecting the strength of an electromagnet Introduction: An electromagnet consists of a long coil of wire wound on a soft iron core. When current flows through the wire the soft iron core becomes magnetized by induction and thus acts as a magnet till the current flows. The strength of an electromagnet can be affected by various factors such as no.of coils, specific resistance of the wire used to coil the core, the thickness of the wire etc. In this experiment the effect of changing the no.of coils and the thickness of the wire used will be determined. Aim: To determine the effect of changing the no.of coils and the thickness of wire used on the strength of an electromagnet. Hypothesis:
Apparatus:
Procedure:
A modification in procedure:
Safe Test:
...read more. The length by which the wire was cut every time the no,of coils was reduced was also kept constant.The electromagnet was realigned every time its position was moved to changed the no of coils. Observation: Raw Data Table Table 1: Table showing the variation in distance at which the compass deflects with change in no.of coils and diameter of the wire.
The only raw data that may be processed is the diameter of the wire to find the cross-sectional area of the wire. Processed Data Table Table 2: Table ...read more. Graphical Analysis: This graph clearly shows the variation in extent of magnetic field at every thickness for the different no.of coils. The difference in the values of different thicknesses is quite noticeable and also constant. Conclusion:After close observation and analysis, it can be concluded that as the no.of coils on an electromagnet increase, so does the extent of the field created by it. Also, as the thickness of the wire used for coiling increases the resistance of the wire drops and the electromagnet becomes stronger. The hypothesis stated earlier has been proved right. Evaluation: Overall, this experiment proved to be quite successful apart from the minor inaccuracies in readings. However, this experiment could have been made better:
...read more. This student written piece of work is one of many that can be found in our GCSE Electricity and Magnetism section. Found what you're looking for?
What affects the strength of electromagnet?The strength of magnetic field of an electromagnet depends on: Number of turns: The strength of magnetic increases on increasing the number of turns of the winding. Current: The strength of magnetic field increases on increasing the current through the solenoid.
How can the strength of an electromagnet be changed?The strength of an electromagnet can be increased by increasing the number of loops of wire around the iron core and by increasing the current or voltage.
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