affect - effect
Affect /ə^fekt/ is a verb. To affect someone or something means to cause them to change, often in a negative way.
There are many ways in which computers can affect our lives.
The disease affected Jane's lungs.
Effect /ɪ^fekt/ is usually a noun. An effect is something that happens or exists because something else has happened.
The report shows the effect of noise on people in the factories.
This has the effect of separating students from teachers.
You can say that something has a particular effect on something else.
Improvement in water supply can have a dramatic effect on health.
These changes will have a significant effect on our business.
Effect is sometimes a verb. If you effect something that you are trying to achieve, you succeed in achieving it. This is a formal use.
The new law will give us the power to effect change.