2 The downward-sloping AD curve An increase in the price level causes a fall in real money balances (MP) (实际货币余额)， causing a decrease in the demand for goods services. AD CHAPTER 9 Introduction to Economic Fluctuations slide 10slide 10 An increase in the price level causes a fall in real money balances (M/P ) (实际货币余额), causing a decrease in the demand for goods & services. Y P AD 2