🔍 Key Concepts

• Series vs. parallel circuits — how current finds a path through switches and lamps • Open vs. closed switches — an open switch is like a broken wire; a closed switch completes the path • Common return/ground — all lit lamps must have a complete path from positive to negative

💭 Think About

• Trace the path of current from the power source: for each branch, ask yourself, ‘Is there an unbroken path through switches and lamps back to the return?’ • Look carefully at which lamps are in series with a switch: if any switch in that series path is open, will current reach that lamp? • Compare the options: which answer choices include any lamp that clearly has a broken path at either the supply or the return side?

✅ Before You Answer

• For each lamp number, verify whether it has a complete path from the positive side of the source to the negative side with no open switches in between • Check if any lamp in a choice is connected through more than one open switch — if so, that choice is likely wrong • Confirm that lamps that are clearly bypassed by a closed parallel path (or isolated by an open switch) are not counted as lit in your final choice