End of Test - Measurement Techniques

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• 0.1 ms div^-1

• 1 ms div^-1

• 10 ms div^-1

• 100 ms div^-1

A student wishes to determine the density ρ of lead. She measures the mass and diameter of a small sphere of lead:

mass = (0.506 ± 0.005) g

diameter = (2.20 ± 0.02) mm.

What is the best estimate of the percentage uncertainty in her calculated value of ρ ?

• 1.7%

• 1.9%

• 2.8%

• 3.7%

Two quantities p and q are directly proportional to each other.

Experimental results are taken and plotted in a graph of q against p.

Which graph shows there were random errors in the measurements of p and q?

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A man of mass 75.2 kg uses a set of weighing scales to measure his mass three times. He

obtains the following readings.

mass / kg

reading 1 80.2

reading 2 80.1

reading 3 80.2

Which statement best describes the precision and accuracy of the weighing scales?

• not precise to ± 0.1 kg and accurate to ± 0.1 kg

• not precise to ± 0.1 kg and not accurate to ± 0.1 kg

• precise to ± 0.1 kg and accurate to ± 0.1 kg

• precise to ± 0.1 kg and not accurate to ± 0.1 kg

A micrometer screw gauge is used to measure the diameter of a small uniform steel sphere. The micrometer reading is 5.00 mm ± 0.01 mm.

What will be the percentage uncertainty in a calculation of the volume of the sphere, using these

values?

• 0.2%

• 0.4%

• 0.6%

• 1.2%

A student intends to measure accurately the diameter of a wire (known to be approximately 1 mm) and the internal diameter of a pipe (known to be approximately 2 cm).

What are the most appropriate instruments for the student to use to make these measurements?

• calipers, calipers

• calipers, micrometer

• micrometer, calipers

• micrometer, micrometer

The power P dissipated in a resistor of resistance R is calculated using the expression

 $P\ =\ \frac{V^2}{R}$  
where V is the potential difference (p.d.) across the resistor. The percentage uncertainty in V is 5% and in R is 2%.What is the percentage uncertainty in P ?

• 3%

• 7%

• 8%

• 12%

A micrometer screw gauge is used to measure the diameter of a copper wire.

The reading with the wire in position is shown in diagram 1. The wire is removed and the jaws of

the micrometer are closed. The new reading is shown in diagram 2.

What is the diameter of the wire?

• 1.90 mm

• 2.45 mm

• 2.59 mm

• 2.73 mm

A digital meter has an accuracy of ±1%.

The meter is used to measure the current in an electrical circuit.

The reading on the meter varies between 3.04 A and 3.08 A.

What is the value of the current, with its uncertainty?

• (3.06 ± 0.02) A

• (3.06 ± 0.04) A

• (3.06 ± 0.05) A

• (3.06 ± 0.07) A