Electrical resistance and power

What is consumer electrical resistance and how is it measured.
What is consumer power and how is it measured.

Warm-up

It is said that an LED lamp is much more economical than an incandescent lamp. Really? How to determine this?

Let's first recall what we have dealt with in the previous lessons.

Slide to recall previously learned material.

The aim of this lesson is to get acquainted with the concepts of resistance and power of an electrical consumer.

It is not possible to "teach clearly" these concepts in a class structured like this. The idea is rather that we use again the skill learned in the previous lessons to measure the voltage and current in the circuit with a tester and do simple calculations with the results, which give understandable and expected results - we learn that the LED lamp is indeed more economical than the incandescent lamp.

We will get acquainted with Ohm's law later. Here we give simplified definitions in a simplified manner.

Familiarize yourself with the concept of electrical resistance. Answer the question.

Familiarize yourself with the concept of electricity consumer capacity. Answer the question.

We measure the resistance and power of an incandescent lamp and an LED lamp

First, a classic test directly using Ohm's law, where the resistance of the light bulb is determined.

Measure the amount of current passing through the light bulb and the voltage at the light bulb terminals. Calculate the resistance of the light bulb using the voltage and current. Answer the question.

Measure the amount of current passing through the LED lamp and the voltage at the terminals of the incandescent lamp. Calculate the resistance and wattage of the LED lamp using the voltage and current. Answer the question.

Let's analyze the results

Lõpuks võrdleme mõõtmistulemusi ja teeme oma järeldused.

Compare the resistances and wattages of an incandescent bulb and an LED bulb. Answer the question.

Selle tunni lõpetuseks võiks teha ühe harjutuse, mis tuletab meelde varemõpitut ning kasutab ära andmeid, mis me eelmistes töölehtedes oleme mõõtnud.

Assemble a circuit where an incandescent lamp and an LED lamp are connected in series. Complete the table by measuring currents and voltages in different parts of the circuit. Answer the question.

Incandescent lamp and electric motor in one circuit

Summary

A conductor (electrical appliance) is characterized by electrical resistance. The conductor prevents the directed movement of charged particles and thereby affects the current strength.

The resistance can be calculated from the formula

R = \frac{U}{I}

new $U$ is the voltage across the conductor and $I$ is the current in the conductor. The resistance symbol is $R$ . The unit of resistance is $1$ ohm ( $1 Ω$ ).

The speed of doing work is described by the physical quantity power. The power of electrical equipment can be calculated from current and voltage:

P = U I

Control questions

Let us have two consumers with different electrical resistance, through which an electric current of the same strength passes. Is more power released in a consumer with higher or lower resistance?

Here we find out

Incandescent or LED?

Review: Circuits, measuring voltage and current

Resistance

Power

Determination of electrical resistance and power of an incandescent lamp

Determining the electrical resistance and power of an LED lamp

Let's compare the resistances and powers of an incandescent lamp and an LED lamp

Series connection of an incandescent lamp and an LED lamp

Incandescent lamp and electric motor in one circuit

Electrical resistance

Power