Lab 7 Hints

Activity 1C, 1B

Activity 1A

Battery or power supply (in previous picture)

Activity 2Oscilloscope lets you see the voltage across capacitor as a function of time

Function generator mimics a battery that switches sign

Capacitor

Resistor

Circuit

Wires from function generator

Capacitor

Resistor

Connect oscilloscope

Capacitor

Oscilloscope leads

Set up the function generator to mimic a battery that switches

polarity“Square wave” mimics a battery that switches back and forth

Adjusting the oscilloscope

1) Set to “Auto”

2) Set to “Gnd”

3) Adjust until line is in middle of screen. This is the zero voltage line.

4) Set to “DC”

You should see this

Adjust voltage scale (vertical) here.

Adjust time scale (horizontal) here

Adjust the vertical scale (pull center) and trigger level until you get this….

Measure the time constant

• Time that it takes rising curve to reach 5/8 of the maximum

Time constant

Measure the time constant

• Time that it takes falling curve to reach 3/8 of the maximum

Time constant