CCT CCT Electrical & Electronic Calibration 2

Question 1

What is the primary use of a Josephson junction array in electrical metrology?

Accepted Answer

Realizing the SI unit of voltage with quantum-level accuracy

Answer

Measuring high-frequency RF signals

Answer

Testing insulation resistance

Answer

Generating AC waveforms for oscilloscope calibration

Question 2

When calibrating an insulation resistance tester (megohmmeter), what type of reference standard is used?

Accepted Answer

A precision resistor with a known high-resistance value

Answer

A standard battery

Answer

A calibrated oscilloscope

Answer

A low-resistance shunt

Question 3

What effect does temperature have on precision resistors used as calibration standards?

Accepted Answer

Temperature causes resistance values to change, described by the temperature coefficient of resistance (TCR)

Answer

No effect — resistors are temperature independent

Answer

Temperature only affects capacitors, not resistors

Answer

High temperature increases accuracy

Question 4

What is the purpose of a 'guard' terminal on a precision resistance standard?

Accepted Answer

To eliminate leakage currents from affecting the measurement

Answer

To protect the resistor from physical damage

Answer

To connect the resistor to a safety ground

Answer

To provide a voltage reference point

Question 5

Which parameter is calibrated when verifying an oscilloscope's timebase accuracy?

Accepted Answer

Horizontal sweep speed (time per division)

Answer

Voltage amplitude

Answer

Input impedance

Answer

Trigger sensitivity

Question 6

What is 'self-heating error' in precision electrical measurements?

Accepted Answer

Resistance change in a resistive element caused by the power dissipated by the measurement current flowing through it

Answer

Errors caused by warm-up time of the instrument

Answer

The effect of room temperature on a voltage calibrator

Answer

Error introduced by a faulty thermocouple in the instrument