Physics 145 Introduction to Experimental Physics I

Instructor: Karine Chesnel Office: N319 ESC

Tel: 801- 422-5687 kchesnel@byu.edu

Office hours: on appointment

Class website:

http://www.physics.byu.edu/faculty/chesnel/physics145.aspx

Lab 10Labview

Lab 10: Labview

Follow the Manual

• L10.1: Chapter 1: Building a Virtual Instrument (VI)

• L10.2: Chapter 2: Analyzing and saving a signal

• L10.3: Chapter 3: Expanding the features of a VI

• L10.4: Chapter 4: Data Acquisition

Applications Pendulum experiment

Rotation frequency of rotor

Physical experiment

User Interface

VI

Goal: Build a front panel

Knob:to control aparameter

Graph: to visualize signalin real time

STOP buttonto stopmeasuring

Preview of the Front panel

Preview of the Block Diagram

• Changing signal type

Front panel

Run Stop

• Adding Controls

• Wiring objects on the Block diagram

• Running the VI

• Modifying the signal(ex: arithmetic operation)

Block diagram

• Displaying two signals on the graph

• Customizing the knob

• Customizing the waveform

Goal: Generate and analyze a signal

Peak to peakamplitude

Warning LED:if signal exceedsa certain level

Simulated signal

• Open a blank VI

• Build the block diagramBlock diagram

• Analyzing the amplitude of the signal

• Setting the warning level

• Adding a warning light

• Saving the data to file

• Open a blank VI

• Adding an Express VI that simulates the signal

• Modifying the signal

Block diagram

• Configure the VI to run continuously until user stops it

• Controlling the speed ofthe execution (time delay)

• Using a table to display data

Goal: Adjust the data sampling and display data

Average value

Table ofAveragedvalues

Goal: Acquire real experimental data Using the DAQ assistant system

• Open a blank VI

• Insert the DAQ assistant

• Enter Input signal (Analog Input)

• Select physical channel

• Adjust input range

• Adjust number of samples

DAQ assistant

• Graphing data from DAQ

Pendulum experiment

F ma

mg kx mx

time

• Adjust rate and number of samples• Adjust custom scaling

Rotation frequency of rotor

Laser light blocked by tape

Periodic signal

Measure period as function of voltagePlot rotor frequency (Hz) vs voltage (V)

laser

Rotoraxel

w/ tape

photodiode