CBSE Class 10 Science 2018 · Paper 31(B)/C · Question 27(a)

Any four of the following: (i) The connecting wires should be thick copper wires, and their ends should be cleaned with sandpaper before connecting. (ii) All connections should be tight. (iii) The ammeter should be connected in series with the resistors and the voltmeter in parallel across the combination of both resistors, with the + terminal of each meter joined to the + side of the battery. (iv) The current should be passed only for a short time, while taking readings (the key is plugged only then), so that the resistors do not get heated. (v) The pointers of the ammeter and the voltmeter should read zero when no current flows, and the readings should be taken without parallax. (Other correct precautions, such as using meters of suitable range, also earn credit.)