Page 180 - NCERT Science Class 10 English Medium

7 Electric bulb or

8 A resistor of resistance R

9 Variable resistance or rheostat or

10 Ammeter

11 Voltmeter

11.4
OHM’S LAW
11.4 OHM’S LA
11.4
11.4 OHM’S LAOHM’S LAWW
11.4 OHM’S LAWW
Is there a relationship between the potential difference across a conductor
and the current through it? Let us explore with an Activity.
Activity
11.1
Activity
Activity 11.1
Activity 11.1
Activity 11.111.1
n Set up a circuit as shown in Fig. 11.2,
consisting of a nichrome wire XY of length,
say 0.5 m, an ammeter, a voltmeter and
four cells of 1.5 V each. (Nichrome is an
alloy of nickel, chromium, manganese, and
iron metals.)
n First use only one cell as the source in the
circuit. Note the reading in the ammeter I,
for the current and reading of the voltmeter
V for the potential difference across the
nichrome wire XY in the circuit. Tabulate
Figure 11.2
Figure 11.2
Figure 11.2
Figure 11.2
Figure 11.2 Electric circuit for studying Ohm’s law
them in the Table given.
n Next connect two cells in the circuit and
note the respective readings of the ammeter and voltmeter for the values of current through
the nichrome wire and potential difference across the nichrome wire.
n Repeat the above steps using three cells and then four cells in the circuit separately.
n Calculate the ratio of V to I for each pair of potential difference V and current I.
S. Number of cells Current through Potential difference V/I
No. used in the the nichrome across the (volt/ampere)
circuit wire, I nichrome
(ampere) wire, V (volt)
1 1
2 2
3 3

4 4
n Plot a graph between V and I, and observe the nature of the graph.

Electricity 175

2024-25