Physics 7 Lesson 23: Magnetic effects, chemical effects and physiological effects of electric current
1. Summary of theory Tóm
1.1. Word effect
a) Magnetic properties of magnets
Magnets have magnetic properties because they have the ability to attract objects made of iron or steel.
Magnets have the ability to rotate magnet needles. Each magnet has 2 poles (there is strong attraction).
The poles interact with each other.
– Comment: When there is an electric current, the young iron core is capable of:
The coil wound around a young iron core, with current passing through it, is an electromagnet.
An electromagnet is magnetic because it has the ability to attract iron or steel objects and rotate the magnet’s needle
c) Learn about electric bells
Electric motors such as electric fans, water pumps… operate based on the mechanical effect of electric current
Electric current has a magnetic effect because it can rotate the needle of a magnet
1.2. Chemical effect
– When electric current flows through the copper salt solution, it separates the copper from the solution, forming a copper layer on the coal bar connected to the negative pole of the power source. We say that electric current has a chemical effect.
- Application in electro-casting industry, electroplating (gold plating, silver plating, copper plating…), metal refining and battery charging…
1.3. Physiological effects
– If electric current passes through the body of a person or animal, it can cause convulsions, cardiac arrest, suffocation, nerve paralysis and possibly death. We say that electric current has a physiological effect.
- Electric current can be dangerous to human life. So be very careful when using electricity, especially with the home electrical network.
- In medicine, people can still use electric current to cure some diseases.
- Stimulator: Once the heart has stopped beating, people can use electric shock therapy to try to stimulate the heart to beat again in the hope of sustaining life.
- Acupuncture machine: Cure stroke, headache, back pain, mouth distortion, abdominal bloating, osteoarthritis, vision loss…
⇒ In addition to the above effects, we can say that electric current has a mechanical effect. Because when current flows through the motor, it rotates the motor. The application of mechanical effects is to manufacture electric motors used in daily life such as electric fans, water pumps, blenders…
2. Illustrated exercise
Question 1: The charcoal stick connected to the cathode was previously black. After a few minutes of testing, what color is it coated with?
The part of the coal ingot attached to the negative pole of the power supply gradually changes from black to a brick red color.
The current passing through the copper salt solution causes the coal ingot to be connected to the cathode covered with a copper layer.
Verse 2: Observe the experiment to investigate the chemical effect of electric current and answer the questions
Observe the light when the switch is closed and indicate that the salt solution of copper sulphate (CuSO4) is a conductor or an insulator?
When K is closed, the light is on.
⇒ Show that an electric current flows through the circuit (that is, an electric current flows through the copper salt solution) the copper sulphate salt solution is a conductor.
3.1. Essay exercises
Question 1: When conducting an experiment for an electric current to flow through a frog’s thigh, the frog’s thigh contracts, which is the effect of the current?
Verse 2: Why does the bell keep ringing as long as the switch is closed?
Question 3: When the current flows through the copper salt solution, after a while, a thin layer of copper clings to the coal bar connected to the negative electrode of the power source. Can this phenomenon be explained by the effect of electric current?
Verse 4: What is the effect of electric bells working?
3.2. Multiple choice exercises Bài
Question 1: If we touch a bare wire (without insulation) the current will pass through the body causing convulsions, burns that can even be fatal due to:
A. Physiological effects of electric current
B. Chemical effect of electric current
C. Magnetic effect of electric current
D. Thermal effect of electric current
Verse 2: When an electric current is passed through a hair dryer, what effects does the current cause?
A. Words and chemistry
B. Optics and chemistry
C. Magnetic and Heat
D. Magnetic and Optical
Question 3: Which of the following objects causes a magnetic effect?
A. A new battery is placed separately on the table.
B. A piece of nylon that has been vigorously rubbed.
C. A current-carrying coil of wire.
D. A piece of duct tape.
Verse 4: Which statement below is incorrect?
A. The coil of wire wrapped around an iron core when an electric current flows through is capable of attracting iron and steel objects.
B. The coil of wire wrapped around an iron core when an electric current flows through is capable of rotating the magnet needle.
C. The coil of wire wrapped around the iron core is capable of attracting all iron and steel objects and rotating the magnet needle.
D. The coil of wire wrapped around an iron core when an electric current flows through acts (role) like a magnet.
Through the lecture The magnetic effect, chemical effect and physiological effect of this electric current, students need to complete some of the objectives given by the lesson such as:
Describe an experiment or operation of a device that exhibits the effect of an electric current.
Describe an experiment or a practical application of the chemical effect of electric current.
List some applications of the magnetic effect of electric current. Manifestations due to physiological effects of electric current passing through the human body.