Which leads do you have to use on the switch in order to get the light bulbs to light? 2. When you shunt the light bulb, what happens to the circuit? 3. When you remove the shunt, what happens to the light bulb? Why? 4. What is the purpose of the fuse? Further Investigations: What would happen to the protection capabilities of a fuse wire if it were made from a larger diameter wire? D. Best grade level?