With the aid of at least one diagram and examples, explain why the demand curve for a normal good (define this term) is downward sloping.
A demand curve shows the relationship between the quantities of a good consumers (or a consumer) are willing and able to buy during a particular time period, and their respective prices, ceterius paribus (all other things being equal). A normal good is a good for which the demand varies positively with income; this means that as income increases, demand for the good (Q1 to Q2) increases at every price level e.g. P1; a rightward shift of the demand curve of the commodity (D1 to D2). The demand curve for a normal good is downward sloping because of diminishing marginal utility, and the substitution and income effects.