The table below shows a student testing small cells used to power a warning light on a hiking box. Each cell contains a zinc electrode, a copper electrode a...
Question 1 Report
The table below shows a student testing small cells used to power a warning light on a hiking box. Each cell contains a zinc electrode, a copper electrode and the same acid solution. Fig. 1 shows how the cells can be connected. The student keeps the temperature at 20 degrees C and measures the potential difference after one minute.
| Number of identical cells in series | Potential difference / V |
|---|---|
| 1 | 1.08 |
| 2 | 2.16 |
| 3 | 3.25 |
(a) Complete the table heading sentence: cells connected in the arrangement in Fig. 1 are connected in ______. [2]
(b) Use the results to calculate the expected potential difference for four identical cells. [3]
(c) Suggest why the measured value for three cells is 3.25 V rather than exactly 3.24 V. [3]
Answer Details
(a) The cells are connected in series. In a series connection, the voltages, or potential differences, add together. [2 marks]
(b) One cell supplies 1.08 V, so for four identical cells:
\[1.08\times4=4.32\text{ V}\]
The expected potential difference is 4.32 V. [3 marks]
(c) The value 3.25 V is close to the expected \(3\times1.08=3.24\text{ V}\). The small difference can result from measurement uncertainty or meter resolution. The cells may not be exactly identical, and factors such as temperature or electrode condition may vary slightly. [3 marks]
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