The colour coded carbon resistance has three bands. the bands from left are blue, yellow and red the resistance is

Options

A. `6400 Omega +- 20 % `
B. ` 642 +- 20 % `
C. ` 6420 +- 10 % `
D. ` 46 00 +- 5% `

Answer

To solve the problem of determining the resistance from the color-coded bands on a carbon resistor, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Color Bands**: The question states that the color bands from left to right are blue, yellow, and red.

2. **Determine the Values for Each Color**:
- According to the standard color code for resistors:
- Blue corresponds to the digit **6**.
- Yellow corresponds to the digit **4**.
- Red corresponds to a multiplier of **10** (which can also be expressed as \(10^1\)).

3. **Calculate the Resistance**:
- The resistance (R) can be calculated using the formula:
\[ R = (First\ Digit \times 10 + Second\ Digit) \times Multiplier \]
- Substituting the values:
\[ R = (6 \times 10 + 4) \times 10 \]
- This simplifies to:
\[ R = (60 + 4) \times 10 = 64 \times 10 = 640 \, \Omega \]

4. **Consider Tolerance**:
- Since the question does not specify a tolerance value, we can assume a standard tolerance of **±20%** for carbon resistors.
- Therefore, the final resistance can be expressed as:
\[ R = 640 \, \Omega \, \pm \, 20\% \]

5. **Final Answer**:
- The resistance is \(640 \, \Omega \, \pm \, 20\%\).