Embedded Files
Lab instruction PDF
Lab instruction PDF
Needed equipments
Needed equipments
wire strippers
lamp holder
multimeter
wattmeter
anmeter
stove element
New terms used
New terms used
A stove element is a circular heating device converting electric energy into heat to cook.
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Types of stove elements
Coiled heating elements: These are found in the cooktop of electric stoves and are exposed on the surface.
Radiant heating use ceramic glass surface to heat food.
Oven elements are found in electric and convection cookers ovens and transfer heat.
How they work
Electric current passes into a resistor in a heating element, which makes heat--a process called Joule heating.
The heat element glows red if it heats up as the filament is a resistor and is hot.
A multi-meter is
A multi-meter is
A variac (or variable auto transformer) is a type of autotransformer giving adjustable AC voltage.
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Its distortion free output is ideal for sensitive electronic applications, testing devices for approval.
How they work
Variacs have tapped inductors--a donut-shaped wire coil.
A conductive slider/"tap", moves with the inductor's length.
The slider lets electricity "tapped" at any point on the winding, producing a specific voltage output.
A control (e.g. knob) is used to adjust the voltage output.
A anmeter is
A wattmeter
A GW Instek is a modern power meter measuring power, voltage, current, frequency and power factor simultaneously.
An ohmmeter is a
Ohm's Law-With Gwinstek-1
Ohm's Law-With Gwinstek-1
A light bulb has low resistance if it's cold.
If its temperature increase, so does its resistance.
This protective plate has 2 coil underneath.
Only one of the coils are used in the video.
Without anything connected to the stove element and measure the resistance of the cold stove element--being ~90 ohms, but can get ~100 ohms hot.
We use a stove element as its resistance is unchanged with the temperature.
We apply voltages on the stove element with a variac (right of image).
The variac's scale isn't accurate and can be only be right after reading its output, which is brought onto a panel with an on/off switch, a black and white buttons (variac output terminals) and a green button (ground).
To hook up the circuit, hook up the wires of the variac's output connected to the wire of the stove elements' 2 inputs.
The AC voltmeter is placed across (in parallel with) the stove element.
(misheard in video)The clanpon and meter is clamped around one of the variac's power leads.
The lab experiment's table should show the voltage from 0-120 V.
At 0 V position, shut off the power switch, which must be 0.
The in to the power on adjusts the variac to 10 V and measure the current.
Increase the value to 20 V and proceed to 120 V.
After all current measurements, with a calculator, calculate the power dissipated by the stove element and the resistance at different voltages/temperatures.
The stove element's resistance shouldn't change much with temperature.
Experiment with light bulb
Experiment with light bulb
Measure a cold light bulb's resistance.
A 100 W light bulb is ~12-14 ohms.
The settup is the same as with the stove element: a variac's output is linked to the light bulb.
The voltmeter is placed across the with the light bulb in parallel.
(misheard in video)And a clamp on n meter goes onto one of the power leads.
Increase the light bulb's voltage according the experiment's table and record the corresponding current.
With a calculator, calculate the power dissipated by the light bulb and the resistance dissipated at each temperature.
higher temperature = brighter light bulb and brighter resistance
Hook a light bulb to the 100 V disconnect.
Insert a power meter between the disconnect and light bulb.
Misheard words in video
To connect a power meter, hook up the live wire from the disconnect to power meter's line in.
Hook up the disconnect's neutral to the neutral in of the power meter.
The power meter's output is the line out and the neutral out, which feed the light bulb.
References
References
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