# Maintenance: Create a bulk quote request Digital Multimeters In iKnow This is the first lesson in the iKNOW® Multimeters Library. The lesson presents the types of multimeters. The lesson describes the display area, function switch, and leads and jacks on a digital multimeter. Wye and Delta Connections In iKnow The tenth lesson in the iKNOW Electrical Theory for Troubleshooters Library, this lesson discusses Wye and Delta configurations and explains the relationship between phase and line voltages in various connections, and demonstrates the application of the formula that shows this relationship. Inductance In iKnow This is the seventh lesson in the iKNOW Electrical Theory for Troubleshooters Library. This lesson builds on the information presented in the lesson, Electromagnetism. Types of induction, phase, and the effect of induction in AC circuits are covered. Three-Phase Circuits In iKnow This is the ninth lesson in the iKNOW® Electrical Theory for Troubleshooters Library. This lesson defines 3-phase AC, describes the components and operating principle of 3-phase generators, and using the formula for frequency, shows how rotor speed and the number of poles is related to frequency. Parallel Circuits In iKnow This is the fourth lesson in the iKNOW Electrical Theory for Troubleshooters Library. This lesson describes the behavior of voltage, current, and resistance in a parallel circuit. The learner is also instructed in the identification of the series and parallel portions of a series-parallel circuit. Electromagnetism In iKnow This sixth lesson in the iKNOW Electrical Theory for Troubleshooters Library uses animations and demonstrations to explain the principles of magnetism, including flux density and electromagnetic induction. The lesson also shows how to plot a sine wave using a graph. Series Circuits In iKnow This is the third lesson in the iKNOW Electrical Theory for Troubleshooters Library. The lesson presents the operation of a series circuit and trains participants in the identification of simple schematic symbols used to represent components in a series circuit. The behavior of current, resistance, and current in a series circuit, and the used of Kirchhoff's Voltage Law to find total voltage are also covered. Protective Helmets In iKnow This is the seventh lesson in the iKNOW Electrical Safety Library. This lesson explains the protection provided by helmets, and the proper methods of inspection, wearing and maintaining a helmet. Introduction to Electricity In iKnow This is the first lesson in the iKNOW® Electrical Theory for Troubleshooters Library. This lesson uses animation to demonstrate atomic structure, electricity, and how a simple circuit operates. The lesson also explains the characteristics of good conductors and insulators.