Exchange rates: WACE Year 12 Economics Unit 3
“Explain how a floating exchange rate is determined by demand and supply, the causes of appreciation and depreciation, and the effects of exchange rate movements on the economy”
A floating exchange rate is set where demand for the Australian dollar equals supply in the foreign exchange market. An appreciation (a higher AUD) makes exports dearer and imports cheaper; a depreciation does the reverse. The main drivers are commodity prices, interest rate differentials, and relative economic conditions.
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What this dot point is asking
SCSA wants you to explain how the floating AUD is determined, identify what shifts demand and supply, and analyse the effects of appreciation and depreciation on trade, inflation, the current account and growth. Expect a forex diagram and a short or extended response.
The foreign exchange market
Since the dollar was floated in December 1983, the exchange rate is set by the interaction of demand for and supply of Australian dollars in the foreign exchange market, with no day-to-day RBA target.
The exchange rate is the price of one currency in terms of another, for example AUD/USD. It can be quoted bilaterally or as the Trade Weighted Index (TWI), a weighted average against the currencies of Australia's major trading partners.
Demand for AUD
The demand curve for AUD slopes downward (a lower AUD makes Australian assets and goods cheaper, raising quantity demanded). Demand comes from foreigners who need AUD to:
- Buy Australian exports (iron ore, coal, LNG, education, tourism).
- Invest in Australian assets (direct and portfolio investment).
- Speculate on a rising AUD.
Supply of AUD
The supply curve slopes upward. Supply comes from Australians who sell AUD to obtain foreign currency to:
- Buy imports.
- Invest abroad or pay interest and dividends to foreign lenders.
- Speculate on a falling AUD.
The equilibrium exchange rate is where the demand and supply curves intersect. On a diagram, the vertical axis is the price of AUD (for example in USD) and the horizontal axis is the quantity of AUD traded.
Causes of appreciation and depreciation
An appreciation (rise in the AUD) follows an increase in demand for AUD or a fall in supply. A depreciation (fall in the AUD) follows a fall in demand or a rise in supply. Key drivers:
- Commodity prices and the terms of trade. Higher iron ore and energy prices raise export revenue and demand for AUD, appreciating the dollar. This makes the AUD a "commodity currency".
- Interest rate differentials. If the RBA cash rate is high relative to the US Federal Reserve and other central banks, foreign capital chases higher returns, raising demand for AUD. In 2022 to 2024, US rate rises that outpaced RBA rises weighed on the AUD.
- Relative inflation and growth. Stronger Australian growth and confidence attract investment.
- Expectations and speculation. Around 60 percent of forex turnover is speculative; sentiment can move the rate sharply.
- Global risk sentiment. The AUD is a "risk-on" currency that tends to fall during global financial stress.
Suppose the iron ore price rises sharply. Export revenue increases, so foreign buyers demand more AUD to pay for Australian ore. The demand curve for AUD shifts right. With supply unchanged, the equilibrium exchange rate rises (appreciation), say from US 0.66 to US 0.70. Exporters now receive fewer AUD per USD of sales, while imports become cheaper for Australian consumers.
Effects of exchange rate movements
Appreciation (higher AUD)
- Exports become more expensive in foreign currency, reducing export competitiveness and volumes.
- Imports become cheaper, raising import volumes and lowering imported inflation.
- The balance on goods and services tends to worsen (after the J-curve lag).
- Helps the RBA fight inflation by lowering import prices.
- Hurts trade-exposed industries (mining, agriculture, tourism, education).
Depreciation (lower AUD)
- Exports become cheaper and more competitive, raising export volumes.
- Imports become dearer, encouraging import substitution but adding to imported inflation.
- The balance on goods and services tends to improve over time.
- Acts as an automatic shock absorber: when commodity prices fall, the AUD usually falls too, cushioning export industries.
The floating AUD automatically cushions external shocks. When global demand and commodity prices collapse (as in the 2008 GFC and early COVID-19), the AUD falls, supporting exporters and stabilising income. This flexibility is a key argument for the float over a fixed exchange rate.
The J-curve
After a depreciation, the balance on goods and services may worsen before it improves. In the short run, contracts are fixed and volumes are slow to adjust, so the higher cost of imports dominates. Over time, volumes respond and the balance improves, tracing a J-shape.
An appreciation is not automatically good and a depreciation is not automatically bad. An appreciation helps consumers and fights inflation but hurts exporters; a depreciation helps exporters but adds to inflation. Always evaluate the effect on the specific group and objective in the question rather than labelling a rising dollar as good.
Exam-style questions
Questions in the style of SCSA exam questions on this dot point, each with a worked answer. They are written by ExamExplained unless tagged "Past paper"; the year shows the paper a question is modelled on.
WACE 2022-style10 marksUsing a foreign exchange market diagram, explain how a rise in commodity prices causes the Australian dollar to appreciate, and analyse the effects of that appreciation on the Australian economy.Show worked answer →
A 10 mark response needs the demand-and-supply diagram, the appreciation mechanism, and the effects.
Diagram and mechanism. Draw the forex market with the price of AUD (in USD) on the vertical axis and the quantity of AUD on the horizontal axis, with a downward-sloping demand curve and upward-sloping supply curve. A rise in commodity prices lifts Australian export revenue, so foreign buyers demand more AUD to pay for iron ore, coal and LNG. The demand curve shifts right, raising the equilibrium exchange rate (an appreciation).
Effects. A higher AUD makes exports dearer in foreign currency (reducing competitiveness and volumes) and imports cheaper (raising import volumes and lowering imported inflation). The balance on goods and services tends to worsen after the J-curve lag, and the RBA's task of fighting inflation is helped by cheaper imports. Trade-exposed industries (manufacturing, tourism, education) are squeezed.
Markers reward a correct forex diagram, the demand-shift mechanism, and a balanced set of effects across trade, inflation and competitiveness.
WACE 2023-style6 marksExplain how a floating exchange rate acts as an automatic shock absorber for the Australian economy.Show worked answer →
A 6 mark response needs the float mechanism and the cushioning effect.
Under a float, the exchange rate is set by demand and supply with no RBA target, so it adjusts automatically to changing conditions. When global demand and commodity prices collapse (as in the 2008 GFC and early COVID-19), Australian export revenue falls, demand for AUD falls, and the dollar depreciates.
The depreciation makes exports cheaper and more competitive and imports dearer, supporting export industries and national income exactly when they are under pressure. This automatic stabilising adjustment cushions external shocks and is a key argument for the float over a fixed exchange rate.
Markers reward the demand-driven depreciation in a downturn and the competitiveness cushion it provides.