Final answer:
The operating resistance of a 30-watt light bulb designed for a 28-volt system is 26 ohms.
Step-by-step explanation:
The operating resistance of a 30-watt light bulb designed for a 28-volt system can be found using Ohm's law. Ohm's law states that resistance (R) is equal to voltage (V) divided by current (I), so in this case, R = V/I. In this case, the voltage is 28 volts and the power is 30 watts. Since power is equal to voltage times current (P = V × I), we can rearrange the equation to solve for current, I = P/V. Plugging in the values, we get I = 30/28 = 1.07 amps. Now we can substitute the values of voltage and current into Ohm's law to find the resistance, R = V/I = 28/1.07 = 26 ohms.