Q. Consumption function in the AS-AD model?
Consumption. Suppose that P increases by say 10% whereas real GDP (Y) is constant. Nominal GDP and nominal national will now have increased by 10%. If your income increases by 10% and prices increase by 10%, it's reasonable to assume that your consumption (in nominal terms) will increase by 10% (nothing has changed in real terms). This means that demand for real consumption C is unchanged.