Physics Measurement Techniques Quiz

A whale produces sound waves of frequency 5 Hz. The waves are detected by a microphone and displayed on an oscilloscope. What is the time-base setting on the oscilloscope?

• 0.1 ms div -1

• 1 ms div -1

• 10 ms div -1

• 100 ms div -1

The angular deflection of the needle of an ammeter varies with the current in the ammeter as shown in the graph. Which diagram could represent the appearance of the scale on this meter?

• Diagram A

• Diagram B

• Diagram C

• Diagram D

The strain energy W of a spring is determined from its spring constant k and extension x. The spring obeys Hooke’s law and the value of W is calculated using the equation shown. What is the percentage uncertainty in the calculated value of W?

• 6%

• 10%

• 16%

• 32%

An analogue ammeter has a pointer which moves over a scale. Following prolonged use, the pointer does not return fully to zero when the current is turned off and the meter has become less sensitive at higher currents than it is at lower currents. Which diagram best represents the calibration graph needed to obtain an accurate current reading?

• Diagram A

• Diagram B

• Diagram C

• Diagram D

A power supply of electromotive force (e.m.f.) 50 V and negligible internal resistance is connected in series with resistors of resistance 100 Ω and 5 Ω, as shown. What are suitable ranges for the ammeter and for the voltmeter?

A single sheet of aluminium foil is folded twice to produce a stack of four sheets. The total thickness of the stack of sheets is measured to be (0.80 ± 0.02) mm. This measurement is made using a digital caliper with a zero error of (−0.20 ± 0.02) mm. What is the percentage uncertainty in the calculated thickness of a single sheet?

• 1.0%

• 2.0%

• 4.0%

• 6.7%

In an experiment to determine the acceleration of free fall g, a ball bearing is held by an electromagnet. When the current to the electromagnet is switched off, a clock starts and the ball bearing falls. After falling a distance h, the ball bearing strikes a switch to stop the clock which measures the time t of the fall. If systematic errors cause t and h to be measured incorrectly, which error must cause g to appear greater than 9.81 m s –2?

• h measured as being smaller than it actually is and t is measured correctly

• h measured as being smaller than it actually is and t measured as being larger than it actually is

• h measured as being larger than it actually is and t measured as being larger than it actually is

• h is measured correctly and t measured as being smaller than it actually is

A student is given a reel of wire of diameter less than 0.2 mm and is asked to find the density of the metal. Which pair of instruments would be most suitable for finding the volume of the wire?

• A balance and micrometer

• Metre rule and micrometer

• Metre rule and vernier calipers

• Micrometer and vernier calipers

Four different students use a ruler to measure the length of a 15.0 cm pencil. Their measurements are recorded on four different charts. Which chart shows measurements that are precise but not accurate?

• Chart A

• Chart B

• Chart C

• Chart D

In a simple electrical circuit, the current in a resistor is measured as (2.50 ± 0.05) mA. The resistor is marked as having a value of 4.7 Ω ± 2 %. If these values were used to calculate the power dissipated in the resistor, what would be the percentage uncertainty in the value obtained?

• 2%

• 4%

• 6%

• 8%