Accuracy of cesium clock is

Options

A. 1 part in `10^7`
B. 1 part in `10^(13)`
C. 1 part in `10^(-7)`
D. 1 part in `10^(-13)`

Answer

To determine the accuracy of a cesium clock, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Cesium Clocks**: Cesium clocks are atomic clocks that use the vibrations of cesium atoms to measure time. They are known for their high precision and accuracy.

2. **Defining Accuracy**: The accuracy of a clock refers to how closely the clock's timekeeping matches the true time. For cesium clocks, this is often expressed in terms of parts per billion or trillion.

3. **Evaluating Options**: The options given in the question are:
- One part in \(10^7\)
- One part in \(10^{13}\)
- One part in \(10^{-7}\)
- One part in \(10^{-13}\)

4. **Researching Cesium Clock Accuracy**: It is known that cesium clocks have an accuracy of about one second over a period of approximately 30 million years, which translates to an accuracy of about one part in \(10^{17}\).

5. **Selecting the Correct Answer**: Based on the known accuracy of cesium clocks, the correct answer is:
- One part in \(10^{17}\)

### Final Answer:
The accuracy of a cesium clock is approximately **one part in \(10^{17}\)**.

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