1) i = sin t

We saw this curve above, except now we are using i for current and t for time. These are very common variables in trigonometry.

Period = 2π

Amplitude = 1

2) v = cos t

Once again, we saw this curve above, except now we are using v for voltage and t for time.

Period = 2π

Amplitude = 1

3) i = 3 sin t

Period = 2π

Amplitude = 3

4) E = -4 cos t

The variable E is used for "electro-motive force", another term for voltage.

Period = 2π

Amplitude = 4

Notice that:

• The negative in front of the cosine has the effect of turning the cosine curve "upside down". That is, it is a mirror image in the horizontal t axis.
• Amplitude is a positive number (it is a distance)