CCT Calibration Techniques & Procedures 4

Question 1

A calibration standard with a stated uncertainty of ±0.01% and a 95% confidence level means:

Accepted Answer

There is a 95% probability that the true value falls within ±0.01% of the standard's reported value

Answer

Uncertainty at a stated confidence level means the true value lies within the stated interval with that probability, not that it is guaranteed to be within that interval.

Question 2

Which method is most appropriate for calibrating a high-accuracy platinum resistance thermometer (PRT) in the range of 0°C to 660°C?

Accepted Answer

Fixed-point calibration at ITS-90 defined phase transition temperatures

Answer

ITS-90 fixed points (such as the freezing points of tin, zinc, and aluminum) provide the most accurate reference temperatures and are the accepted method for primary PRT calibration.

Question 3

When documenting a calibration, the minimum traceability statement on the certificate must include:

Accepted Answer

The reference standards used, their calibration certificates, and the accrediting body

Answer

Traceability documentation must identify the standards used and link them to an unbroken chain back to national or international standards through their certificates and the body that accredited them.

Question 4

A calibration technician is using a fluke 5522A multi-product calibrator to calibrate an oscilloscope. To verify the oscilloscope's vertical gain accuracy, the technician should output:

Accepted Answer

A sine wave at a known frequency and amplitude

Answer

Vertical gain accuracy is verified by comparing the oscilloscope's displayed amplitude of a sine wave to the calibrator's precisely known output amplitude at a specific frequency.

Question 5

The 4:1 test accuracy ratio (TAR) rule specifies that the calibration standard's accuracy should be at least 4 times better than the tolerance of the instrument being calibrated. This ratio exists primarily to:

Accepted Answer

Limit the probability that standard uncertainty contributes significantly to conformance decision errors

Answer

A 4:1 TAR ensures the standard's error is small relative to the UUT tolerance, reducing the risk of incorrectly accepting or rejecting the UUT due to standard uncertainty.

(CCT) Certified Calibration Technician Practice Test

(CCT) Certified Calibration Technician Practice Test

CCT Calibration Techniques & Procedures 4