- Which material among the ones in the graph * is nonohmic material? Diode Light bulb Resistor Diode and Light bulb

Step 1 ：Analyze the voltage-current relationship for each material

Step 2 ：Diode: non-linear (nonohmic)

Step 3 ：Light bulb: non-linear (nonohmic)

Step 4 ：Resistor: linear (ohmic)

Step 5 ：\( \boxed{\text{Final Answer: Diode and Light bulb}} \)