Static Electricity Basics
What is static electricity?
The accumulation of an electric charge, either positive or negative, on the surface of an object, resulting from a temporary imbalance of electrons.
What is charging by friction?
What is the process of transferring charge by rubbing two objects together, where one gains electrons and the other loses them?
What is the difference between charging by contact and induction?
Charging by contact transfers charge through direct touch, while induction rearranges charges without direct contact.
What is grounding?
What is the process of removing excess electric charge by connecting an object to the Earth?
Why does your hair stand up when taking off a sweater in winter?
Taking off a sweater can cause electron transfer, making your hair strands repel each other (since like charges repel).
What happens when a neutral object gains electrons?
The object becomes negatively charged.
How does the electrostatic series help predict charges?
It shows which materials gain or lose electrons when rubbed together. Materials higher in the series lose electrons and become positive, while materials lower gain electrons and become negative.
How can a negatively charged rod charge a neutral object without touching it?
The negative rod repels electrons in the neutral object, making the side closest to the rod positive. If grounded, electrons leave, and the object remains positive after removing the rod.
How does a lightning rod protect a building?
The rod provides a safe path for lightning to travel to the ground instead of striking the building.
Why do socks sometimes stick to other clothes after being in the dryer?
Rubbing in the dryer creates friction, transferring electrons between clothes. This causes static cling as opposite charges attract.
What can cause static electricity to build up?
Friction, Induction, Contact
Predict what happens when an acetate rod rubbed with hair is brought near an ebonite rod rubbed with wool.
The acetate rod is positive (loses electrons to hair), and the ebonite rod is negative (gains electrons from wool). Since opposite charges attract, the rods will be attracted to each other.
Why does a plastic comb rubbed with silk attract your hair?
The plastic comb becomes negatively charged when rubbed with silk. When brought near hair strands, it induces a positive charge, attracting it.
Why do people sometimes get shocked when touching a doorknob?
When you walk on a carpet, electrons transfer to your body. When you touch the doorknob, the charge suddenly jumps, creating a shock.
Why does rubbing a balloon on your head let you "pick up" small bits of paper?
The balloon becomes negatively charged when rubbed on hair. It induces a positive charge on the paper, making it stick to the balloon
What type of material is more likely to create a static charge?
Explain how a negatively charged balloon can charge a neutral conducting sphere without touching it.
The negative balloon repels electrons in the sphere, pushing them to the far side. This leaves the near side positively charged, creating attraction without direct contact. If the sphere is grounded, electrons escape, leaving it with a permanent positive charge.
A neutral metal sphere is placed near a negative balloon. What happens to the charge distribution?
Electrons in the metal sphere move away from the balloon, leaving the near side positive and the far side negative
Why do airplanes release static electricity before refueling?
Static charge buildup on the plane could cause sparks, which are dangerous around fuel. Grounding cables remove excess charge before refueling.
How does electrostatic painting work?
The paint is given a charge (usually negative) as it leaves the spray nozzle, while the object being painted is given the opposite charge (usually positive or neutral). Since opposite charges attract, the paint particles are drawn evenly to the object, reducing waste and creating a smooth, even coat
Explain why a charged balloon sticks to a wall.
The balloon is negatively charged, and the neutral wall has positive and negative charges. The negative charges in the wall are repelled, leaving the positive charges closer to the balloon. This creates an attractive force (induced charge separation).
A hockey puck is rubbed on a dog's fur, then touches a neutral electroscope. The pith ball repels an ebonite rod. What charge must the ebonite rod have? Explain.
When the dog rubs against the rubber puck, the puck becomes negatively charged. When it touches the electroscope, charge is transferred, making the pith ball negative. Since the pith ball repels an ebonite rod, the ebonite must also be negative. This follows the law that like charges repel.
Balloon A must either be neutral or positive.
Explain how static electricity is discharged in a thunderstorm.
Electrons in the clouds move to the bottom, making the ground positive. When the charge difference is large enough, electrons jump to the ground as lightning.
How do electrostatic precipitators help reduce pollution?
In an electrostatic precipitator, polluted air passes through charged plates or wires that give dust and smoke particles a negative charge. These charged particles are then attracted to positively charged collection plates, where they stick and are removed from the air, reducing pollution.