The following set of labs cannot all be performed in one quarter. You must therefore select the ones which follow your own preference. If you are teaching a lab in conjunction with another instructor, then you should agree on one choice and order of labs to be performed as otherwise, the complications of stocking equipment on the storage carts becomes overly problematic for the stockroom help.

We ask that you take care to see that your students put the lab equipment neatly and carefully back on the storage carts. Organizing equipment back on the storage cart should be done by the students not the instructor, but if the instructor doesn't care how the equipment is returned, neither does the student; please help keep the carts organized by asking your students to return the equipment as they found it.

The order of the labs is not mandatory but is probably best used as presented. Some labs may be omitted, but it is recommended that at least the OHM'S LAW lab and the two oscilloscope labs be performed.

Please have failed equipment returned with a tag (the tags are found near the door to the stockroom) by the students and not just put back on the cart to be found broken by another lab.

Any suggestions for expansion, elaboration, or correction should be directed to the authors; your comments are welcome.
 

This set of lab experiments is designed to introduce the student to the measuring techniques and concepts found in DC and AC circuits analysis, magnetic and electric phenomenon, and the conceptual physical processes that explain the circuit's behavior.

In physics 4B, the lab skills of any given group of students typically has a vast range due to some people's prior knowledge and experience; it is not uncommon that a highly experienced electronics technician is in the same lab as a neophyte who does not know a resistor from a capacitor and certainly does not know how to use an oscilloscope. These labs require no in depth background in electronics; they are designed to take a student with no prior skill, to a level where he should be able to use an oscilloscope (and all lab equipment) to take measurements with confidence and to understand the physical basis of why these things in the circuits are occurring. As well, the experienced tech should be able to deepen his knowledge with simple experiments that he no longer has time to perform.

Not all of these labs can be performed in one quarter's time. You must check with your instructor to find the order of the specific labs that you will be doing.

Since most of these labs involve the use of numerous pieces of equipment, it is imperative that the equipment be put away neatly, back on the lab carts. The electrical equipment you will be using in this lab is often extremely expensive to buy and fix. Please show respect for your equipment and you will be respected for it.

If you have any equipment that is malfunctioning, please "tag" the equipment with the tags found near the stockroom door, and return the equipment to your instructor.

Lastly, when you have completed your lab, please return your equipment to the storage carts as neatly, or more neatly, as you found it at the beginning of the lab; this will greatly facilitate the next's labs ability to get started quickly.
 
 

In learning to deal with circuit construction, the novice student may need the following guidelines. Please read and study the advice carefully since the equipment you will be using throughout the 4B labs is delicate and quite expensive; abuse of this equipment will not be tolerated and connecting a circuit incorrectly may damage power supplies or measuring instruments. Please check with your instructor to see if your circuit is correct before turning on the power; this way, if you "fry" an instrument, it will be your instructor's fault, not yours!

Eleven things to remember:

1. Assemble your circuits with the power disconnected and off.

2. Double check all connections before turning on the power.

3. If you have any doubts, have your instructor check your circuit before turning on the power.

4. How to turn the power on and off: Make sure all voltage and current setting knobs on the power supply are turned to zero. Turn the power switch on. Slowly turn up the power to the desired level. Turning off the power is the reverse of the above; turn down the power to zero then turn off the power. This method introduces less current shock to the circuitry.

5. When in doubt, do not use both hands at the same time when checking equipment with the power on. Put one hand behind your back so you don't forget. Touching your circuit with two hands at once means you could possibly apply a voltage across your two hands and thereby completes a circuit that contains your heart. A current through your heart of 0.1 A for a few seconds will induce fibrillation.⁽¹⁾

6. Before you change a setting on any device predict the outcome first by physical reasoning. This is most important if you want to understand what you're doing.

7. For non-auto scaling meters, like the VOM and DMM's, start with the dial setting with the largest numerical value. Do this for voltmeters and ammeters alike. This method will help you avoid damaging the meter by sending too much current through it on a low setting. Start with the largest setting and move down gradually to smaller settings until you have the setting that provides the most significant figures (for digital readouts) or where the scale increments are furthest apart. Also, never measure a resistance value while a current is already through that resistor!

8. Never pull any plug out of its jack by pulling on the wire. Pull on the plug housing instead or you may pull the wire right out of the plug.

9. Avoid mishandling the equipment by dropping it or putting it on the table carelessly.

10. If something is broken don't put it back on the cart. Have your instructor check the equipment and fill out a repair tag describing the problem. You will not be punished for reporting broken equipment.

11. Put away your equipment as neatly as you found it. Coil all power cords. Put away connecting wires by type and color. Make sure all equipment is turned off. See that your lab table area is cleared and clean. Garbage goes in the garbage cans not around your table.

Circuit building tips:

1. Color code your wiring as best as possible. Use red wire for high potentials, black wire for ground and green for low potentials.

2. Set up the actual circuit first and then insert the necessary test equipment. In our class the actual circuit alone is usually simple. Things start getting complicated when test equipment is applied. If you have trouble setting up circuits follow this procedure.
 

3. Constantly check connections to make sure they are not loose (do this safely!). Fifty percent of the problems students have are due to bad connections.

4. Layout your circuit in the simplest possible manner with the fewest possible wires. This makes it much easier to troubleshoot your circuit if you encounter problems.

Types of equipment and measuring instruments you will use (see the appendix for more detailed information on this equipment):

1. VOM: Stands for volt-ohm meter although it can usually measure current as well. This is the classic analog meter.

2. DMM: Digital Multi-Meter. In this class, a small, hand held, battery powered instrument that does essentially what a VOM does except it gives you a digital readout. Be careful with these meters they can give spurious readouts and are more delicate than they appear.

3. HP-DMM: The Hewlett-Packard digital multi-meter is powered by a cord and provides highly accurate and precise values. It has auto-scaling and control of the significant figure in the display. Nonetheless it still does essentially the same job as a VOM.

4. DC power supply (also called a "TPS" for transistorized power supply): The Heath Kit DC power supply is a delicate beast. Be careful not to demand too much current. This should be an item to check when you are troubleshooting a circuit.

5. High Voltage power supply: This Heath Kit power supply should be treated with respect as its high voltage could harm you.

6. HP function generator: This quality instrument provides alternating voltage at varying frequencies in three different signal forms: sinusoid, square, and triangle.

7. Dual trace oscilloscope: This instrument will be the basic measuring tool for many labs. It is by far the most complicated instrument to master in this lab, yet its basic function is simpler than even the VOM's.

Types of circuit elements you will encounter:

1. Resistor: A device or a property of another device that "resists" the flow of charge through it.

2. Capacitor: A device that stores electrical energy and that will tend to pass alternating current (AC) but not direct current (DC).

3. Battery: A portable source of power, usually of low voltage.

4. Inductor: This is used in AC applications and exploits the properties of changing magnetic flux.

5. Diode: This device will allow charge to pass through it in one direction only.

Schematic symbols used in circuit diagrams:

Not available yet.
 
 

Common concepts: (also see the glossary)

1. Voltage: A difference in electric potential between (or across) two points. The two points may be in space or actually located on a specific body or circuit.

2. Current: The flow of charge through a material body, or a vacuum, with respect to time.

3. Resistance: The opposition a body presents to the flow of charge though it.

4. Capacitance: The ratio of the amount of charge a body holds to the electric potential it consequently possesses (C = Q/V).

5. Inductance: The property of a circuit component (or even a circuit) that resists the change of magnetic flux through it.

6. Ohms' Law: A basic although not fundamental law commonly applied in circuit analysis .It is a linear relation between voltage, current and resistance .Bear in mind that although Ohms' Law is linear this does not mean all circuits elements are linear in that they obey Ohms's Law, indeed most circuit elements are non-linear and do not obey Ohms' Law.