| Prajapati went to the market to buy some cells for his TV remote. But later on, he felt that those cells were not working properly. So, in order to rectify his doubt, he took those cells to his college's Physics laboratory and checked their emf with the help of potentiometer. |
| He was surprised to see that the emf values were less than those printed on the cells by the manufacturer. He then complained the consumer forum regarding this and received the deserving response. |
| Read the above passage and answer the following questions. |
| (i) What values are displayed by Prajapati? |
| (ii) Why does Prajapati especifically used only potentiometer to find out the value of emf of the cells instead of voltmeter. |
Answer:
(i) Values displayed by Prajapati are as follows : (a) General awareness (b) Use of scientific knowledge. (ii) Potentiometer is based on null point method. On the other hand, voltmeter draws current at the time of measurement of potential difference across the cell. So, it does not give the correct value of emf.
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