Final answer:
A blue band on a resistor represents the digit 6 according to the resistor color code system. Colors are used to denote numbers, with each color corresponding to a specific number from 0 to 9.
Step-by-step explanation:
The digit represented by a blue band on a resistor answer is 6. To read the value of a resistor, you need to refer to the color-coding system used to denote the individual resistance values. This system uses colored bands where each color corresponds to a specific number. According to this system, black is 0, brown is 1, red is 2, orange is 3, yellow is 4, green is 5, blue is 6, violet is 7, gray is 8, and white is 9.
Therefore, a blue band on a resistor indicates the number 6. So the correct answer to the question 'Which digit is represented by a blue band on a resistor?' is C. 6.