Electric Motors (DC)?

Question

hey i have four questions for yas most apprieciated if you can help!!!
Question 1
Where does the energy that makes the DC electric motor work originally come from?

Question 2
What difficulties would you have measuring the current flowing through a DC electric motor when it is operating?

Question 3
Please Explain how you would calculate the resistance (in ohms) of a DC electric motor circuit.

Question 4
PLease name as many appliances that have electric motors in them

please and thank-you if ya answered!!! PEACE OUT :D

Answer 1

1. The power for a DC motor can be from different sources. It may come from a battery such as small toy trucks or the blower motor on your car. It may come from AC power through rectification. Such as in many industrial applications.

2. It is done commonly in troubleshooting. I personally would use a clamp on ammeter. Simply put it around one of the wires going to the motor and read the readout on the meter. Smaller motors this would be harder. You could also use a regular ammeter by placing the ammeter in series with the motor but that would require some wiring.

3. To calculate the resistance in ohms of the DC motor you would need to know a couple of things. First of all what is the voltage applied to the motor. Second of all, how much current did you measure in step 2. Now use Ohm's law where R = E/I. R is the resistance in ohms, E is the voltage and I is the current.

4. Many appliance have electric motors however, not many household appliance would use a DC motor because it would take additional equipment to convert the household AC to DC and since there are small AC motors readily available this is not done. Washers and Driers have a drive motors and timer motors. A microwave with a turning table would have a motor. Blender, refrigerator, furnace, mixer, garbage disposal, can opener....too many to hit them all. Now, some smaller household electronics such as computers, video games, vcr's dvd players, walkman's, etc. would have DC motors.

Answer 2

1. The battery or the power supply serving the motor.

2. You can use a clip-on ammeter to measure the current. However depending on what the motor is doing, the current will fluctuate with the work being performed by the shaft of the motor. (i.e. the more load on the motor, the more amps being drawn by the motor.)

3. Measure the voltage across the leads of the motor and use measure the current with the ammeter. Then use Ohm's Law to compute the resistance. V / I = R.

4. Appliances with spinning parts generally have motors. Walk around your house and look at anything that plugs or uses batteries. Here are just a few examples.

CD, DVD, and cassette players, computer, fan, refrigerator, dish washer, microwave oven (the fan and the turn table), clock, garage door opener, air conditioner, furnace, vacuum cleaner, just about every power tool, etc.

Answer 3

1) Are you asking how does a DC electric motor produce energy? The simple answer is that by changing a magnetic field around a coil of wires, you induce an electric field. Inside of a conductive piece of wire an electric field will "push" on electronic particles (like electrons and protons) and force them to drift towards the area of lowest (or highest depending on the particle) area of potential energy. Theres quite a bit of calculus involved in a better explanation though.

2) Well practically it would be near impossible to go near an electric DC motor while in operation. Essentially is a big coil of wires with magnets spinning around it. Aside from being shocked, I dont think you could get close enough to do any type of measurements with a DMM.

3) I suppose your asking how to calculate the internal resistance of a device. There are several ways to do this, depending on how much you know about circuits. One way is to apply a known load to a circuit and measure the voltage drop across it. You can then do a bit of voltage division and come up with an easy answer. This is due to something called the loading effect which basically says that as the load on a circuit increases the effect of the internal resistance of a source (dc motor) decreases.

4) I'm sure you can figure this one out.