What is the ratio of potential difference and current known as?

What p.d. is needed to send a current of 6 A through an electrical appliance having a resistance of 40 Ω

An electric circuit consisting of a 0.5 m long nichrome wire XY, an ammeter, a voltmeter, four cells of 1.5 V each and a plug key was set up.

(i) Draw a diagram of this electric circuit to study the relation between the potential difference maintained between the points 'X' and 'Y' and the electric current flowing through XY.

(ii) Following graph was plotted between V and I values:

What would be the value of ratios when the potential differences us 0.8 V, 1.2 V and 1.6 V respectively?

What conclusion does you drawn from the values?

(iii) What is the resistance of the wire?

The values of potential difference V applied across a resistor and the corresponding values of current I flowing in the resistor are given below :

Plot a graph between V and I, and calculate the resistance of the resistor.

Name the law which illustrated by the above V-I graph.