Product name: Demonstration Electromagnetic Relay Overview A compact teaching relay designed for middle school physics classes to demonstrate the basic structure and working principle of electromagnetic relays. Simple to connect and observe, it illustrates how an electromagnet operates an armature to switch normally open and normally closed circuits. Key benefits Teaches core concepts clearly: Visible electromagnetic coil, iron core armature, and separate contact system make it easy for students to see and understand how relay action works. Easy integration with classroom equipment: Supplied for use with a 9V DC power supply and compatible with indicator lights, demonstration motors, and other controlled instruments for hands on experiments. Adjustable for reliable demonstrations: A spring screw allows fine tuning of contact pressure and travel to ensure consistent switching and clear operation. Durable and portable: Lightweight and compact, suitable for classroom handling and lab benches. Specifications Size: 155 x 105 x 75 mm Weight: 200 g Materials: Plastic base, solenoid coil, iron core armature Main components: Electromagnetic system consisting of coil and iron core armature; contact system with one normally open contact and one normally closed contact How it works Close K4 to allow current through electromagnet M. The energized electromagnet draws down armature P, closing the normally open contact and completing the controlled circuit. Open K4 to remove current. Electromagnet M loses magnetism and spring B pulls armature P back up. The normally open contact opens and the normally closed contact is connected via K2. Adjust the spring screw on the iron core to change spring tension and contact gap, ensuring reliable engagement and clear switching behavior during demonstrations. Practical applications and scenarios Classroom demonstration: Use with a 9V DC supply and an indicator lamp to show students the sequence of energizing the coil, armature movement, and contact switching. Simple control experiment: Combine with a demonstration motor to demonstrate remote switching and basic automatic control circuits. Lab exercises: Allow students to measure coil current, observe contact states, and practice adjusting the spring screw to study contact mechanics and relay performance. What is included Demonstration electromagnetic relay ready for 9V DC operation and connection to external controlled devices for teaching experiments. This relay provides a hands on, reliable way to explore electromagnetic switching and basic control circuits, while remaining compact and classroom friendly.