Casio fx-7400G PLUS Booklet page 24

EE-2 Ohm's Law
Determine the slopes of the graphs shown below.
Expression 1
4 = a
a = 1
Therefore: y = x
k Back to Ohm's Law
Getting back to Ohm's Law, consider the relationship
proportional expression we discussed on the previous page.
If we substitute I for y and E for x,
This results in the proportional expression
to E. In other words, doubling or tripling the voltage value also causes the current value to
double or triple.
y
4
3
2
1
0 1 2
4
a
becomes
1
3 4 5 6 7
Expression 2
2 = a
a = 2 / 3
I = E/R
1/R
.
I = 1/R E
. If R is constant, then I is proportional
– 21 –
2
x
3
Therefore: y = 2x / 3
. Compare this with the
y = ax