The values of current I flowing in a given resistor for the corresponding values of potential difference V across the resistor are given below:
I (amperes): 0.5 1.0 2.0 3.0 4.0
V (volts): 1.6 3.4 6.7 10. 2 13.2
Plot a graph between V and I plotted by using the given data is shown below:
The graph between V and I plotted by using the given data is shown below:
If we look at the graph, we find that when potential difference V is 8.5 volts, then the corresponding current value is 2.5 amperes. Now, Resistance,
Thus, the resistance of the resistor is 3.4 ohms.
Explain the following:
(a) Why is the tungsten used almost exclusively for the filament of electric lamps?
(b) Why are the conductors of electric heating devices such as bread toasters and electric irons made of an alloy rather than a pure metal ?
(c) Why is the series arrangement not used for domestic circuits?
(d) How does the resistance of a wire vary with its area of cross-section?
(e) Why are copper and aluminium wires usually employed for electricity transmission?