Not alot more to say, currently doing a physics assignment where we have to use a small DC Motor and a Solar Cell. Varying the Load on the motor as to test and Prove/Disprove the Commonly Known Work Function : P = IV
ie.
P = Work (Power);
I = Current;
and V = Voltage

Need a reply ASAP. . .Thanks

 

Responding to [G]eronimo's Tue, May 28, 3:45 pm query:

How about using the motor to lift a known weight, a specified height, in a measured length of time!

Regards,
Phil Corso, PE
(Boca Raton, FL)

 

Hi,

Try thinking of a way to use the power of the motor to increase the potential energy of a mass.

Regards

Peter Whalley
Magenta Communications Pty Ltd
Melbourne, VIC, Australia
e-mail: peter*no-spam*@magentacomm.com.au
delete *no-spam* before sending

 

You won't prove it using a small DC motor. The losses will be very significant, and very difficult to measure directly. In normal motor testing, the output power is measured with a dynamometer. The discrepency between input and output power is assigned to "losses". This is in fact how losses are measured.

At best, you can show that voltage and current are proportional to output power. Since a real lab dynamometer is not within your budget, the method described by Mr. Corso may be best. You may need a gear reduction to make this practical. Keep in mind that any mechanical friction involved will add to unmeasurable losses.


************************
Michael Griffin
London, Ont. Canada
************************

 

Hi,
Try use a DC motor controller with load current feedback-close loop control, you can get P=KIV=C
That mean varying load-varying current-varying motor speed(rpm). small load-high speed, big load-low speed, think about winding machine.