"How to use electrical appliances to work normally" Electric Energy and Electric Power PPT Courseware 3

Description

"How to use electrical appliances to work normally" Electric Energy and Electric Power PPT Courseware 3

Please think about:

1. Can the TV work with two dry batteries?

2. Can ordinary MP3 players be directly connected to household circuits for use?

3. Do you know the meaning of the number marked on the light bulb nameplate?

Rated voltage: The voltage required for normal operation of electrical appliances is called rated voltage.

Rated power: The power consumed when working at rated voltage is called rated power.

Experimental phenomena:

When the voltage applied to the bulb is equal to the rated voltage, _____________

When the voltage applied to the bulb is higher than the rated voltage, _____________

When the voltage applied to the bulb is lower than the rated voltage, _____________

analysis and argumentation

When the actual voltage of an electrical appliance is equal to the rated voltage, its actual power is equal to the rated power;

When the actual voltage of an electrical appliance is higher than the rated voltage, its actual power is greater than the rated power;

When the actual voltage of an electrical appliance is lower than the rated voltage, its actual power is less than the rated power.

Knowledge summary

The actual electrical power consumed by an electrical appliance is not necessarily equal to the rated power.

When U real=U amount, P real=P amount;

When U actual > U amount, P actual > P amount;

When U real

Experiment purpose: measure the electrical power of small light bulbs; understand the relationship between rated power and actual power

Experimental principle: P=UI

Experimental equipment: power supply, switches, wires,

Small light bulb (2.5V), voltmeter, ammeter, sliding rheostat

Precautions:

1. How should the sliding rheostat be connected? Where should the slide be placed before closing the switch? What is the function of the sliding rheostat, and how is it different from the experiment of measuring resistance by voltammetry?

2. How are ammeter and voltmeter connected in the circuit? +, - Are the terminals connected correctly? Is the range selection appropriate?

Example 1: Xiao Ming picked up a light bulb marked "220V, 25W". He connected this light bulb in parallel with a "220V, 40W" light bulb. Which bulb will be brighter when connected to a 220 volt circuit?

Example 2: Connect these two light bulbs ("220V, 25W", "220V, 40W") in series and connect them to a 220-volt circuit. Which light bulb consumes more power? (or whichever is brighter)

Example 3: There is a "110V, 40W" and a "110V, 100W" light bulb. Now connect them in series and connect them to the household circuit. Can you judge whether the two lights can illuminate normally? (The lamp does not burn out)

When doing the experiment of "measuring the rated power of small light bulbs",

(1) It is known that the rated voltage of the small light bulb is 3.8 volts and the rated power is less than 2 watts. When a student connected the circuit, several wires were not connected. As shown in the actual object, please use a pen to represent the wires on the actual diagram. The wires are connected properly (it is required to select the correct range of the voltmeter and ammeter).

(2) When a classmate connected a sliding rheostat, due to a wiring error, the sliding plate P of the sliding rheostat could not change the brightness of the small bulb when it moved. Based on the following two situations, please judge how the student is connected?

The first situation: when the small bulb is brighter, he connects the end points of the two wires to the _____ of the sliding rheostat.

The second situation: when the small bulb is dim, he connects the end points of the two wires to the _____ of the sliding rheostat.

(3) When the circuit is correctly connected and the sliding rheostat is adjusted to make the small bulb glow normally, the ammeter reads _______ ampere as shown in the figure, then the rated power of the small bulb is _______ watts.

After a classmate completed the experiment of "determining the electrical power of a small light bulb" (the rated voltage of the small light bulb used was 2.5 volts), he completed the experimental report in time. He designed the tables in the lab report. If the student's observation of experimental phenomena and recording of data are correct, please point out the errors in the table he designed.

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"How to use electrical appliances to work normally" Electric Energy and Electric Power PPT Courseware 2:

"How to use electrical appliances to work normally" Electric Energy and Electric Power PPT Courseware 2 Teaching Objectives 1. The relationship between the rated rate and actual power of electrical appliances 2. Measuring the rated power of small light bulbs Review review 1. What is called electric power? The electrical work done by current per unit time, it is...

"How to Use Electrical Appliances to Work Normally" Electric Energy and Electric Power PPT Courseware:

"How to Use Electrical Appliances to Work Normally" Electric Energy and Electrical Power PPT Courseware [Learning Objectives] 1. Know the meaning of some parameters marked on the electrical appliance nameplate, and know the rated power and actual power of the electrical appliance. 2. Measure the electrical power of small light bulbs. Can be used Electric power formula to calculate rated...