Basic Electricity - Senior Secondary 2 - Moving coil and moving iron instruments

TERM: 2^ND TERM 

WEEK FOUR

Class: Senior Secondary School 2

Age: 16 years

Duration: 40 minutes of 5 periods each

Date:

Subject: BASIC ELECTRICITY

Topic: MOVING COIL AND MOVING IRON INSTRUMENTS

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

I.) Construct a moving coil instrument

II.) Identify the advantages of a moving coil instrument

III.) Construct a moving iron instrument

IV.) Identify the advantages of a moving iron instrument

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

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

INSTRUCTIONAL PROCEDURES

PERIOD 1-2

NOTE

MOVING COIL AND MOVING IRON INSTRUMENTS

The constructional moving feature of a coil/moving iron instrument involves a coil of wire or a piece of iron that moves in response to the quantity being measured. Below is how a moving coil/iron instruments works: 

1. Construction of Moving Coil Instrument

In a moving coil instrument, a lightweight coil of wire is suspended within the magnetic field of a permanent magnet. When current flows through the coil, it generates a magnetic field that interacts with the magnetic field of the permanent magnet, causing the coil to rotate. This rotation is proportional to the current flowing through the coil, providing a measure of the electrical quantity being measured, such as voltage or current.

Advantages of Moving Coil Instruments

I.) Moving coil instruments offer high accuracy due to their sensitive response to changes in current or voltage.

II.) They typically provide a linear response over a wide range of measurements, making them suitable for precise readings.

III.) Moving coil instruments require low power to operate, making them energy-efficient.

IV.) They exhibit good stability over time, maintaining their calibration and accuracy.

V.) Moving coil instruments have low hysteresis, meaning they respond consistently to changes in the measured quantity, reducing errors.

2. Construction of Moving Iron Instrument

In a moving iron instrument, a lightweight piece of iron is suspended within the magnetic field of a fixed coil. When current flows through the coil, it generates a magnetic field that attracts or repels the iron piece, causing it to move. The movement of the iron piece is proportional to the current flowing through the coil, providing a measure of the electrical quantity being measured.

Advantages of moving iron instruments

Moving iron instruments have several advantages:

I.) They can measure both AC and DC currents and voltages over a wide range, making them versatile for various applications.

II.) Moving iron instruments are mechanically robust and can withstand rough handling and environmental conditions better than some other types of instruments.

III.) They offer reasonably good accuracy for many applications, especially in measuring AC currents and voltages.

IV.) They typically have low power consumption, which is advantageous in battery-powered or low-power applications.

V.) Moving iron instruments are often more affordable compared to other types of instruments, making them a cost-effective choice for many users.

EVALUATION: 1. State 4 advantages of moving coil instruments

2. State 4 advantages of moving iron instruments
3. Describe briefly how a moving coil instruments can be constructed.

CLASSWORK: As in evaluation

CONCLUSION: The teacher commends the students positively