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Static electricity (EdExcel)
Static electricity is the buildup of electric charge on the surface of objects due to contact and friction with other materials.
Electrostatic Charge
What is a charge?
- Objects can have positive or negative charges.
- Like charges repel; opposite charges attract.
- Electric charge is measured in coulombs (C).
How do fields work?
- Electric charges create electric fields in the areas surrounding them.
- Field lines always go away from positive charges and towards negative charges.
How are the positive and negative charges created and considered?
- Electrons are negatively charged particles.
- Negative charges are the result of gaining electrons.
- Positive charges are the result of losing electrons.
What is the difference between conductors and insulators?
- Conductors are materials that allow charge to pass through them.
- Insulators do not allow charge to pass through them.
Charging Methods
The three charging methods are friction, induction, and conduction.
1- Friction:
- Rubbing two insulating materials together (e.g., rubbing a balloon against hair).
2- Induction:
- When a charged material is brought near an uncharged material, it will induce a charge in the uncharged material.
- If a negatively charged rod is brought near an object, it will attract positive charges towards the rod, and the negative charges will gather on the opposite side.
- A positively charged rod will attract negative charges.
3- Conduction:
- Direct contact between a charged object and a conductor (charges transfer).
Electrostatic Forces
Like charges repel each other (positive-positive or negative-negative).
Unlike charges attract each other (positive-negative).
Electroscope
An electroscope is a device used to detect the presence and type of electric charge in an object. It consists of a metal rod/wire, with a knob at the top and two thin metal leaves hanging down. The metal rod is typically encased in a glass/plastic container to protect it from drafts and provide insulation.
Uses of static electricity
There are several uses of static electricity, including inkjet printers, photocopiers, and air purifiers.
Inkjet Printers:
Inkjet printers use static electricity to direct droplets of ink onto paper. Tiny electrically charged droplets are created and controlled to form the desired printed characters or images.
Photocopiers:
Photocopiers utilize static electricity to attract toner (powdered ink) onto paper. The image to be copied is transferred onto a drum, which is then charged with static electricity. The toner sticks to the charged areas, creating a replica of the original image on the paper.
Air Purifiers:
Some air purifiers use static electricity to attract and capture dust, pollen, and other particles from the air. The particles are charged electrically, causing them to be attracted to oppositely charged plates or filters within the purifier.
Static Cling in Clothes:
Static electricity can cause clothes to cling together or to your body. This phenomenon is often reduced using fabric softeners and dryer sheets, which contain substances that reduce static charge buildup, making clothes feel softer and reducing static cling.
Electrostatic Painting:
In industrial applications, electrostatic painting uses static electricity to coat objects with paint. The object to be painted is given a negative charge, while the paint is positively charged. This attraction ensures an even coating of paint and reduces waste.
Electrostatic Precipitators:
Electrostatic precipitators are devices used in industries to remove particles like ash and smoke from exhaust gases. The gases pass through a series of charged plates or wires, where particles acquire an electrical charge and are attracted to oppositely charged plates, effectively removing them from the gas stream.
Electrostatic Dusting Cloths:
Some cleaning cloths are designed to attract dust through static electricity. They have properties that enhance their ability to pick up and hold onto dust particles, making them effective for cleaning surfaces without the need for additional cleaning agents.
Dangers of Static electricity
The dangers of static electricity include fire and explosion hazard, ESD damage, industrial accidents, health risks, damage to products and materials, and earthing.
Fire and Explosion Hazard:
Static electricity can ignite flammable gases, vapors, and dust. In industries such as oil refineries, chemical plants, and grain handling facilities, static electricity can build up on surfaces and discharge as sparks. If these sparks occur in the presence of flammable substances, they can ignite fires or cause explosions.
Electrostatic Discharge (ESD) Damage:
Static electricity can damage sensitive electronic components. When a person or object with a significant static charge comes into contact with electronic equipment (such as computer chips or circuit boards), the discharge can cause irreparable damage, leading to malfunctions or complete failure of the device.
Industrial Accidents:
In industrial settings, static electricity can lead to accidents when it causes unexpected sparks or discharges. For example, in chemical manufacturing or storage facilities, static electricity can ignite or react with chemicals, leading to hazardous situations for workers and equipment.
Health Risks:
While less common, static electricity can sometimes cause discomfort or minor injuries. For instance, a sudden static discharge can startle or cause a brief shock to individuals. In some cases, prolonged exposure to static electricity or repeated shocks may lead to minor skin irritation.
Damage to Products and Materials:
Static electricity can also damage certain materials and products. For example, in manufacturing processes involving plastics or films, static electricity can cause these materials to cling together, leading to production issues or quality defects.
Earthing
The metal cases in electrical appliances can cause hazards. If a live wire comes into contact with the metal case, touching it would cause a dangerous shock. The earth wire provides a low-resistance path to the earth. If the current becomes too large, it will cause a surge in the earth wire, blowing the fuse. The fuse then cuts off the supply of electricity, making the appliance safe.
Static electricity (EdExcel)
Static electricity is the buildup of electric charge on the surface of objects due to contact and friction with other materials.
Electrostatic Charge
What is a charge?
- Objects can have positive or negative charges.
- Like charges repel; opposite charges attract.
- Electric charge is measured in coulombs (C).
How do fields work?
- Electric charges create electric fields in the areas surrounding them.
- Field lines always go away from positive charges and towards negative charges.
How are the positive and negative charges created and considered?
- Electrons are negatively charged particles.
- Negative charges are the result of gaining electrons.
- Positive charges are the result of losing electrons.
What is the difference between conductors and insulators?
- Conductors are materials that allow charge to pass through them.
- Insulators do not allow charge to pass through them.
Charging Methods
The three charging methods are friction, induction, and conduction.
1- Friction:
- Rubbing two insulating materials together (e.g., rubbing a balloon against hair).
2- Induction:
- When a charged material is brought near an uncharged material, it will induce a charge in the uncharged material.
- If a negatively charged rod is brought near an object, it will attract positive charges towards the rod, and the negative charges will gather on the opposite side.
- A positively charged rod will attract negative charges.
3- Conduction:
- Direct contact between a charged object and a conductor (charges transfer).
Electrostatic Forces
Like charges repel each other (positive-positive or negative-negative).
Unlike charges attract each other (positive-negative).
Electroscope
An electroscope is a device used to detect the presence and type of electric charge in an object. It consists of a metal rod/wire, with a knob at the top and two thin metal leaves hanging down. The metal rod is typically encased in a glass/plastic container to protect it from drafts and provide insulation.
Uses of static electricity
There are several uses of static electricity, including inkjet printers, photocopiers, and air purifiers.
Inkjet Printers:
Inkjet printers use static electricity to direct droplets of ink onto paper. Tiny electrically charged droplets are created and controlled to form the desired printed characters or images.
Photocopiers:
Photocopiers utilize static electricity to attract toner (powdered ink) onto paper. The image to be copied is transferred onto a drum, which is then charged with static electricity. The toner sticks to the charged areas, creating a replica of the original image on the paper.
Air Purifiers:
Some air purifiers use static electricity to attract and capture dust, pollen, and other particles from the air. The particles are charged electrically, causing them to be attracted to oppositely charged plates or filters within the purifier.
Static Cling in Clothes:
Static electricity can cause clothes to cling together or to your body. This phenomenon is often reduced using fabric softeners and dryer sheets, which contain substances that reduce static charge buildup, making clothes feel softer and reducing static cling.
Electrostatic Painting:
In industrial applications, electrostatic painting uses static electricity to coat objects with paint. The object to be painted is given a negative charge, while the paint is positively charged. This attraction ensures an even coating of paint and reduces waste.
Electrostatic Precipitators:
Electrostatic precipitators are devices used in industries to remove particles like ash and smoke from exhaust gases. The gases pass through a series of charged plates or wires, where particles acquire an electrical charge and are attracted to oppositely charged plates, effectively removing them from the gas stream.
Electrostatic Dusting Cloths:
Some cleaning cloths are designed to attract dust through static electricity. They have properties that enhance their ability to pick up and hold onto dust particles, making them effective for cleaning surfaces without the need for additional cleaning agents.
Dangers of Static electricity
The dangers of static electricity include fire and explosion hazard, ESD damage, industrial accidents, health risks, damage to products and materials, and earthing.
Fire and Explosion Hazard:
Static electricity can ignite flammable gases, vapors, and dust. In industries such as oil refineries, chemical plants, and grain handling facilities, static electricity can build up on surfaces and discharge as sparks. If these sparks occur in the presence of flammable substances, they can ignite fires or cause explosions.
Electrostatic Discharge (ESD) Damage:
Static electricity can damage sensitive electronic components. When a person or object with a significant static charge comes into contact with electronic equipment (such as computer chips or circuit boards), the discharge can cause irreparable damage, leading to malfunctions or complete failure of the device.
Industrial Accidents:
In industrial settings, static electricity can lead to accidents when it causes unexpected sparks or discharges. For example, in chemical manufacturing or storage facilities, static electricity can ignite or react with chemicals, leading to hazardous situations for workers and equipment.
Health Risks:
While less common, static electricity can sometimes cause discomfort or minor injuries. For instance, a sudden static discharge can startle or cause a brief shock to individuals. In some cases, prolonged exposure to static electricity or repeated shocks may lead to minor skin irritation.
Damage to Products and Materials:
Static electricity can also damage certain materials and products. For example, in manufacturing processes involving plastics or films, static electricity can cause these materials to cling together, leading to production issues or quality defects.
Earthing
The metal cases in electrical appliances can cause hazards. If a live wire comes into contact with the metal case, touching it would cause a dangerous shock. The earth wire provides a low-resistance path to the earth. If the current becomes too large, it will cause a surge in the earth wire, blowing the fuse. The fuse then cuts off the supply of electricity, making the appliance safe.
