What is an electromagnet?, A. A magnet that is always magnetic, B. A magnet that works only when electricity flows, C. A magnet made of plastic, D. A magnet that is stronger underwater, 2. Which material is commonly used as the core of an electromagnet?, A. Wood, B. Plastic, C. Iron nail, D. Rubber, 3. How can you make an electromagnet stronger?, A. Use fewer wire coils, B. Use a weaker battery, C. Wrap the wire loosely, D. Add more coils to the wire, 4. What happens to an electromagnet when the battery is disconnected?, A. Its magnetism stops, B. It keeps working forever, C. It becomes stronger, D. It explodes, 5. Why is an electromagnet useful in machines like junkyard cranes?, A. It is cheap to buy, B. It can stick only to plastic, C. It can be turned ON and OFF, D. It works without electricity.

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