Why does aggregate demand curve slope downward: The downward slope of the aggregate demand (AD) curve reflects the inverse relationship between the overall price level and the quantity of goods and services demanded in an economy.
The aggregate demand curve slopes downward due to the interaction of three key economic principles: the wealth effect, the interest rate effect, and the international trade effect.

Wealth Effect:
As the price level decreases, the real value of consumers’ wealth increases. This means that consumers feel wealthier and more financially secure, which tends to encourage higher levels of consumer spending. When prices are lower, consumers can purchase more goods and services with their existing wealth, leading to an increase in the quantity of goods and services demanded.
Interest Rate Effect:
A decrease in the overall price level leads to a lower demand for money by consumers and businesses. When prices are lower, the real value of money holdings increases. As a result, people need to hold less money to conduct their transactions. This excess money can be invested in interest-bearing assets, such as bonds or savings accounts. The increased demand for such assets pushes up their prices and lowers interest rates. Lower interest rates, in turn, stimulate borrowing and spending by households and businesses, leading to higher aggregate demand.
International Trade Effect:
When a country’s price level falls, its goods and services become relatively cheaper compared to those of other countries. This can lead to an increase in exports and a decrease in imports, boosting net exports (exports minus imports). An increase in net exports increases aggregate demand since a higher level of goods and services is demanded for export.
When these three effects are combined, they contribute to the downward-sloping aggregate demand curve. As the price level falls, consumers feel wealthier, interest rates decrease, and exports become more competitive, leading to an increase in overall demand for goods and services. Conversely, when the price level rises, these effects work in the opposite direction, leading to a decrease in aggregate demand.
Conclusion
In summary, the downward slope of the aggregate demand curve is a result of the interplay between the wealth effect, the interest rate effect, and the international trade effect. These effects lead to changes in consumer spending, investment, and net exports as the price level changes,
creating the inverse relationship between the price level and the quantity of goods and services demanded in an economy.