🔍 Key Concepts

• A toroid is a coil wound around a ring-shaped (doughnut-shaped) core. • Look at how the magnetic core is shaped in each figure (straight bar, rectangular stack, or closed ring). • Distinguish between a simple solenoid (coil on a straight form) and a coil that completely wraps around on itself to form a closed loop.

💭 Think About

• Which figure shows the wire wound around a circular ring so that the start and end of the coil nearly meet, forming a closed loop? • In which figure would the magnetic field lines mostly stay inside a ring-shaped core instead of extending out the ends of a straight core? • Which figures clearly have straight or rectangular cores with exposed ends, and can therefore be eliminated as not being toroidal?

✅ Before You Answer

• Verify which drawing has a doughnut/ring-shaped core instead of a straight or rectangular core. • Check that the winding goes all the way around the ring, not just along one side of a straight bar. • Before choosing, eliminate any figure where the core has two obvious ends sticking out like a bar or transformer leg.