A currency is the only product whose price affects the price of every other product a country buys or sells. When it moves, every import gets dearer or cheaper at once, every exporter's competitiveness changes, and nobody has decided any of it. The exchange rate is a price like any other, set by demand and supply, and the whole topic follows from asking who wants a currency and why.
Exchange rate
The price of one currency expressed in terms of another.
Demand for a currency comes from anyone who needs it. Foreigners buying the country's exports must obtain its currency to pay for them. Foreign investors buying its shares, bonds or property need it. Speculators buy it if they expect it to rise. Tourists visiting need it to spend. Supply of the currency comes from the mirror image: domestic residents buying imports must sell their own currency to obtain foreign currency, as must domestic investors buying foreign assets, speculators expecting a fall, and residents travelling abroad.
Appreciation and depreciation apply to floating rates, where the market moves the price. Revaluation and devaluation apply to fixed rates, where the government deliberately changes the pegged value. Using devaluation to describe a market fall is a persistent error and examiners notice it. If the rate floats, say depreciation.
Floating exchange rate
An exchange rate determined by the demand for and supply of the currency on the foreign exchange market, without government intervention to fix its value.
Foreign currency = domestic amount x exchange rate Domestic currency = foreign amount / exchange rateAlways write the rate with its units, as in $1 = £0.80, before calculating. Most errors in these questions come from multiplying when you should divide, and stating the units makes the right operation obvious.
What an appreciation does to importers and exporters
A currency appreciates from $1 = 4 pesos to $1 = 5 pesos. A domestic exporter sells a machine for 20,000 pesos. An importer buys components priced at $6,000. Calculate the effect on each, and state who gains.
The consequences run through the whole economy. A depreciation makes exports cheaper abroad and imports dearer at home, so export volumes tend to rise and import volumes to fall, which supports domestic output and employment. But dearer imports raise the cost of raw materials and components for domestic firms, and the price of imported consumer goods, so inflation tends to rise. An appreciation does the reverse: it restrains inflation by making imports cheaper but squeezes exporters and the industries competing against imports. Neither direction is straightforwardly good, which is why exchange rate policy is contested.
A country's currency depreciates. Which is the most likely immediate effect?
Which would increase demand for a country's currency on the foreign exchange market?
Draw a foreign exchange market diagram with the exchange rate on the vertical axis and quantity of the currency on the horizontal axis. Show demand and supply meeting at an equilibrium rate. Then show separately the effect of a rise in exports, and the effect of a rise in domestic interest rates attracting foreign investment.
Both shocks shift demand right and appreciate the currency, but for different reasons, and questions expect the reason rather than just the direction. Label the vertical axis with actual units, such as dollars per peso, because 'exchange rate' alone leaves it ambiguous which way an increase means the currency has moved.
Exchange rate systems
Under a floating exchange rate the value is set entirely by demand and supply, with no official intervention. The advantages follow from that freedom. The rate adjusts automatically towards correcting a trade imbalance, since a deficit means more currency supplied than demanded and the rate falls, making exports cheaper. No foreign currency reserves are needed to defend any particular level. And monetary policy is freed to pursue domestic objectives such as inflation and employment, rather than being committed to holding a rate. The disadvantage is volatility, since speculation can move the rate far from anything justified by trade, and uncertainty discourages long-term contracts and investment.
Under a fixed exchange rate the government commits to a particular value and maintains it. To prevent depreciation the central bank buys its own currency using foreign reserves, and raises interest rates to attract inflows; to prevent appreciation it sells its own currency, accumulating reserves. The advantages are certainty for traders and investors, and discipline, since a government cannot inflate its way out of trouble without losing the peg. The costs are severe. Large reserves must be held. Monetary policy becomes hostage to the exchange rate, so interest rates may have to rise in a recession. And an overvalued peg invites speculative attack, because speculators know reserves are finite while their selling need not be.
Most systems in practice lie between. A managed float lets the rate move but with the central bank intervening to smooth volatility or resist movements it judges excessive. A crawling peg fixes the rate but adjusts it in small planned steps, often to accommodate higher domestic inflation. Currency unions abolish exchange rates between members entirely, delivering maximum certainty at the cost of surrendering both monetary policy and the exchange rate as adjustment mechanisms, which is why an asymmetric shock inside a currency union has to be absorbed by wages, prices or migration instead.
Why a fixed rate constrains domestic policy
- A government pegs its currency and commits to defending the rate.
- The domestic economy enters recession, so the appropriate domestic policy is a cut in interest rates to stimulate demand.
- Lower interest rates make domestic assets less attractive to foreign investors, so capital flows out.
- Capital outflow means the currency is being sold, putting downward pressure on the pegged rate.
- To defend the peg the central bank must buy its own currency with foreign reserves, and raise interest rates to attract capital back.
- Raising interest rates is the opposite of what the recession requires, so output falls further and unemployment rises.
- The government must choose between the peg and the domestic economy, and if reserves run down before confidence returns, the choice is made for it and the peg breaks.
This is the impossible trinity in narrative form: a country cannot simultaneously have a fixed exchange rate, free capital movement and an independent monetary policy. It can have any two. Naming that trade-off explicitly is a reliable way into the higher bands.
Practise this chain →Several forces determine a floating rate and questions expect more than trade flows. Relative interest rates drive short-term capital movements and dominate day-to-day changes, since higher rates attract deposits. Relative inflation rates matter over the long run, because a country with persistently higher inflation loses competitiveness and its currency tends to fall, which is the purchasing power parity idea. Trade flows matter through the current account. Speculation can dominate everything in the short run, and is self-reinforcing since expectations of a fall cause selling which causes the fall. Government intervention and confidence in the economy and its institutions matter too.
A country with a fixed exchange rate faces persistent downward pressure on its currency. Which pair of actions would defend the peg?
Draw a foreign exchange market showing the equilibrium rate below a government's target fixed rate. Mark the excess supply of the currency at the fixed rate. Show how central bank purchases of its own currency shift demand right to hold the rate, and mark the reserves used.
The gap between quantity supplied and quantity demanded at the pegged rate is what the central bank must absorb every period, and it is the reason defence is finite. Reserves are a stock and the excess supply is a flow, so a persistently overvalued peg exhausts the stock eventually however large it is. That is the mechanism behind every currency crisis.
Applied context
The collapse of European fixed exchange rate arrangements in 1992 illustrates the impossible trinity in practice. Countries committed to holding their currencies within narrow bands found that domestic conditions calling for lower interest rates conflicted with the rates needed to defend the peg. Speculators, recognising that reserves were finite and the domestic political cost of high rates was rising, sold heavily against the weaker currencies. Several governments spent large fractions of their reserves and raised rates sharply before abandoning the commitment within days. Those that floated subsequently recovered faster than those that persisted with defence.
Use this to make the analytical point that a peg is only credible if markets believe the government will accept the domestic cost of defending it. Credibility, not reserves, is what actually holds a fixed rate.
At A Level the analysis extends beyond the nominal rate. The nominal exchange rate is the market price of one currency in another. The real exchange rate adjusts for relative price levels and is what actually determines competitiveness: a country whose currency depreciates by 10% while its inflation runs 10% above its trading partners has gained no competitive advantage at all. The effective exchange rate is a weighted index against a basket of trading partners' currencies, weighted by trade shares, and it is the right measure when a currency is rising against one partner and falling against another.
Real exchange rate = nominal exchange rate x (domestic price level / foreign price level)A rise indicates a loss of competitiveness, whether it comes from a stronger nominal rate or from faster domestic inflation. This is why a nominal depreciation delivers no lasting gain if it feeds through into domestic prices.
Whether a depreciation has actually improved competitiveness
A country's currency depreciates by 12% over two years. Over the same period its domestic price level rises by 14% while its trading partners' price levels rise by 4%. Assess what has happened to its real competitiveness.
Purchasing power parity theory holds that in the long run exchange rates should move to equalise the price of an identical basket of goods across countries, so a currency with higher inflation should depreciate by the inflation differential. It performs reasonably over long periods and poorly over short ones, and the reasons for the failure are instructive: many goods and services are not traded and cannot be arbitraged, transport costs and trade barriers drive a wedge between prices, and short-run rates are dominated by capital flows rather than by goods. PPP nonetheless matters for comparing living standards across countries, since converting at market rates understates real incomes where non-traded goods are cheap.
Exchange rates connect the domestic economy to the rest of the world and appear throughout the macro syllabus. Monetary policy moves the rate through the interest differential, which is the channel most often omitted from policy answers. The current account depends on competitiveness, so the exchange rate is central to correcting an imbalance, and the Marshall-Lerner condition and the J-curve are analysed in the balance of payments note. Depreciation raises import prices and therefore inflation, connecting to price stability. And PPP conversion is what makes cross-country living standard comparisons meaningful, which links to national income measurement and development.
9708-4.1 · 9708-4.6 · 9708-5.3 · 9708-6.1 · 9708-6.3 · 9708-6.5 · 9708-11.1 · 9708-11.4
Assess whether a floating exchange rate is preferable to a fixed exchange rate for a developing economy. (13 marks)
- Define and frameDefine both systems and note that most real regimes are intermediate. State that 'developing economy' changes the answer, because such economies typically have thinner reserves, higher inflation, foreign currency debt and less institutional credibility, and say you will test the systems against those specific features rather than in the abstract.
- Analysis: the case for floatingAutomatic adjustment towards external balance without reserves being spent. Monetary policy freed for domestic objectives, which matters where unemployment and growth are pressing. No vulnerability to speculative attack on a defended level, since there is no level to defend. Support with a forex diagram showing the rate adjusting to eliminate an excess supply of the currency.
- Analysis: the case for fixingCertainty encourages trade and inward investment, which matters most where foreign capital is scarce. A peg imports monetary discipline and can anchor inflation expectations where a central bank lacks credibility of its own, which is a strong argument in high-inflation economies. It also protects borrowers with foreign currency debt, since depreciation raises the domestic cost of servicing it, a danger largely absent in advanced economies.
- EvaluationWeigh the conditions. The impossible trinity means the real choice is which two of fixed rate, capital mobility and monetary independence to keep, and a developing economy may reasonably choose capital controls to keep the other two. Reserves determine whether a peg is defensible at all. The composition of debt matters: heavy foreign currency borrowing makes floating dangerous. And volatility under floating is worse for economies dependent on a few primary commodity exports, whose prices are themselves volatile.
- JudgementConclude conditionally. A peg is preferable where inflation credibility is the binding problem, where reserves are adequate and where foreign currency debt is large. Floating is preferable where shocks are frequent and asymmetric, where reserves are thin, and where monetary independence is needed for domestic objectives. Note that many developing economies sensibly adopt a managed float as a compromise, and say what determines where on that spectrum a given country should sit.
The impossible trinity is the single most effective organising idea for this question, because it converts a list of pros and cons into a genuine constraint with only three possible resolutions.
Can a government control its exchange rate?
- In the short run intervention works, since a central bank buying or selling in size moves the rate, and coordinated intervention by several central banks is more effective still. The limit is that reserves are finite while private capital flows are vastly larger than any single central bank's holdings.
- Interest rates are the more powerful instrument, because they alter the underlying incentive to hold the currency rather than merely absorbing selling pressure. But using them for the exchange rate means not using them for inflation or output, which is a real cost rather than a technicality.
- Credibility does more work than reserves. A peg markets believe will be defended is rarely tested; one they doubt is attacked regardless of the reserve position, because the speculator's downside is limited and the upside if the peg breaks is large.
- Capital controls can restore control by breaking the trinity, and have been used successfully in some crises. Against that, they deter the long-term foreign investment developing economies need, and they are progressively evaded as markets find routes around them.
- In the long run fundamentals dominate. Persistent inflation differentials, productivity trends and current account positions assert themselves eventually, so intervention can influence the path and the speed but rarely the destination.
- The strongest answers distinguish influence from control, and note that the practical question is not whether a government can fix the rate indefinitely but whether it can smooth adjustment at a cost worth paying.
Three habits protect marks. Label the forex diagram axis with actual units, such as dollars per euro, so it is unambiguous which way a rise moves the currency. State the viewpoint currency in the first line and keep it throughout. And when depreciation is proposed as a cure for a deficit, always raise the real exchange rate point: the nominal gain is eroded by the inflation the depreciation itself causes.