Basic Electricity - Senior Secondary 2 - Measuring instruments: Errors

TERM: 2^ND TERM

WEEK TWO

Class: Senior Secondary School 2

Age: 16 years

Duration: 40 minutes of 5 periods each

Date:

Subject: BASIC ELECTRICITY

Topic: MEASURING INSTRUMENTS: ERRORS

SPECIFIC OBJECTIVES: At the end of the lesson, pupils should be able to

I.) Identify measuring instruments found in combination meters

II.) State the functions of operating devices in measuring instruments

III.) State the functions of controlling devices in measuring instruments

INSTRUCTIONAL TECHNIQUES: Identification, explanation, questions and answers, demonstration, videos from source

INSTRUCTIONAL MATERIALS: Videos, loud speaker, textbook, pictures,

INSTRUCTIONAL PROCEDURES

PERIOD 1-2

NOTE

MEASURING INSTRUMENTS: ERRORS

The following are the types of meters often found in combination meters or AVO meters (Ammeter, Voltmeter, Ohmmeter):

1. Analog Voltmeter (AVO): Traditional voltmeters with analog displays, typically using a moving coil or moving iron mechanism to indicate voltage readings on a scale.
2. Digital Voltmeter (DVM): Voltmeters with digital displays, showing voltage readings as numerical values on a digital screen. They offer high accuracy and precision.
3. Analog Ammeter: Similar to analog voltmeters, analog ammeters use a moving coil or moving iron mechanism to measure and display current flow in a circuit.
4. Digital Ammeter: Digital ammeters display current readings as numerical values on a digital screen, offering accurate measurements with high resolution.
5. Ohmmeter: Measures resistance in a circuit, indicating the resistance value directly on a scale or numerically on a digital display. Modern multimeters often include ohmmeter functionality.
6. Multimeter: Combines the functions of voltmeter, ammeter, and ohmmeter in a single instrument. Multimeters can measure voltage, current, resistance, and sometimes other parameters like capacitance, frequency, and temperature. They are available in both analog and digital versions.

Functions of operating devices and controlling devices in measuring instruments:

1. Operating Devices: Operating devices are components or mechanisms within a measuring instrument that allow users to interact with the device, input data or commands, and initiate measurement processes. These devices include:

I.) Input Mechanisms: These allow users to input data or commands into the measuring instrument.

II.) Measurement Start/Stop Controls: Initiate or terminate measurement processes.

III.) Range Selection Controls: Enable users to choose the appropriate measurement range for the parameter being measured.

IV.) Function Selection Switches: In multifunction instruments like multimeters, these switches allow users to select the specific measurement function they want to use, such as voltage, current, resistance, or capacitance.

2. Controlling Devices: Controlling devices are components or mechanisms within a measuring instrument that enable users to control and adjust various aspects of the instrument's operation, performance, and functionality. These devices include:

I.) Calibration Controls: Enable users to calibrate the measuring instrument to maintain accuracy and reliability. This involves adjusting internal settings or parameters to match known standards.

II.) Zero Adjustment Controls: Some instruments, like certain types of ammeters or voltmeters, require zeroing before use to compensate for any offset or drift in the readings.

III.) Display Controls: These include brightness controls, contrast adjustments, or options for switching between different display modes (e.g., analog or digital) to optimize visibility and readability.

EVALUATION: 1. Identify 5 measuring instruments found in combination meters an indicate their function

2. State 4 functions of operating devices in measuring instruments
3. State 4 functions of controlling devices in measuring instruments

CLASSWORK: As in evaluation

CONCLUSION: The teacher commends the students positively