Joule Formative Assessment: Resistance in a Wire
Band DescriptorsA (lower) / Use simple numbers and words for measurements.
A (upper) / Make choices about the most appropriate units to be used with data.
B (lower) / Use simple equations with units.
B (upper) / Use appropriate equations and calculations with more difficult numbers, including decimal places.
C (lower) / Use equations and rearrange formulae. Use appropriate prefix and significant figures.
Colin Spark, a scientist working for Pearsley Electronics, has been investigating the resistance of different materials ready for their new range of smart phones. The material being tested will be used inside the phone to make the circuits connecting the touch screen to the processors.
This is a diagram showing the circuit he used:
The resistor in the circuit is used to show the material being tested. The ammeter and the voltmeter readings can be used to calculate the resistance of the material.
Q1. The reading on the ammeter when testing a length of Tungsten was 20102. Write this number in words:
……………………………………………………………………………………………………………………………………………...
Q2. When Colin calculated the resistance of the same Tungsten wire his calculator was reading 0.00060. Write this number in words:
……………………………………………………………………………………………………………………………………………...
Q3. Colin changed the Tungsten for a length of Graphite (Carbon) and wrote down the following words in his results table: “zero point zero three nine five”. Write this as a number:
………………………………
Q4.Choose the correct Unit to fill in the gaps in the following report from Colin. Only use Units from the box below. Each Unit can be used once, more than once or not at all
AmpsVoltsOhmsMetres kilo Ohmsmilliamps
“Each material being tested was connected to a power supply. The power supply was used to set the potential difference at 12 …………….
The current in the circuit was measured using the ammeter. This gave readings measured in …………….
Some readings for current were very small and can be recorded in …………….
The resistance of each material is calculated using the potential difference and the current. By dividing the value of potential difference by the current in the circuit the resistance is calculated and measured in ……………. Very large resistances can be recorded in …………….”
Q5. Use the following equation to calculate the resistances of the three wires being tested. Write down all the numbers on your calculator screen:
Resistance = Potential Difference ÷ Current
Name of material / p.d. across the material / Current in the material / Resistance of the materialAluminium / 12 / 40 000
Graphite / 12 / 40
Tungsten / 12 / 20 000
Q6. Use the same equation to calculate the resistances of the next three wires being tested,
Give all your answers to two decimal places (2 d.p.)
Name of material / p.d. across the material / Current in the material / Resistance of the materialSilver / 12.2 / 40.065
Copper / 12.1 / 42.8
Steel / 11.8 / 19.996
Q7. Using the same equation as seen in Q5 and Q6, calculate all the missing values in the table of results below. Colin would like all his answers to be correct to three significant figures:
Name of material / p.d. across the material / Current in the material / Resistance of the materialSilver / 12 V / 80000
Rubber / 9 V / 0.0012
Copper / 12 V / 0.00020
Glass / 0.000012 / 500 000
Aluminium / 6 V / 0.00035
Graphite (carbon) / 1.5 V / 0.38
Tungsten / 20016 / 0.00060