Electric Charge and Atomic Structure

Electric field strength is defined as the force per unit positive charge at a point in an electric field, with SI units of newton per coulomb (N C⁻¹) or volt per metre (V m⁻¹).

Point discharge can be minimized by avoiding pointed or irregular surfaces, which reduce the likelihood of current leakage and sparks. Instead, smooth surfaces should be favored.

Coulomb's law states that the force between two charges is inversely proportional to the square of the distance between them, meaning that as distance increases, the force decreases rapidly. This is characteristic of inverse square relationships.

<p>A full-body metal-foil suit protects operators by allowing electrical charges to redistribute across the surface, preventing electrical current from passing through the body. This is crucial for safety when working with high voltages.</p> Signup and view all the answers

<p>To charge a gold leaf electroscope negatively by induction, a negatively charged object is brought close to the electroscope without touching it, causing electrons in the electroscope to move away from the object, resulting in a net negative charge.</p> Signup and view all the answers

<p>The SI unit of electric charge is the coulomb (C), representing the amount of charge carried by a body.</p> Signup and view all the answers

<p>One coulomb of charge contains about 6.25 × 10^18 electrons.</p> Signup and view all the answers

<p>When a body gains electrons, it becomes negatively charged.</p> Signup and view all the answers

<p>When two like-charged rods, such as two polythene rods, are brought close, they repel each other.</p> Signup and view all the answers

<p>The polythene rod becomes negatively charged as it gains electrons from the cotton cloth.</p> Signup and view all the answers

<p>Unlike charges attract each other because positive and negative charges create a force that pulls them together.</p> Signup and view all the answers

<p>Charge conservation means that an atom never loses or gains protons during charging processes, ensuring atomic identity.</p> Signup and view all the answers

<p>Dust accumulation is more noticeable on CRT screens due to their static charge attracting dust particles more effectively.</p> Signup and view all the answers

<p>Static charge builds up due to friction, causing clothes to cling together.</p> Signup and view all the answers

<p>Precautions are needed to minimize explosion risks from static electricity sparks in the presence of flammable materials.</p> Signup and view all the answers

<p>Touching a charged object while earthed allows excess charge to leave, resulting in a neutral charge when the earth connection is removed.</p> Signup and view all the answers

<p>Free electrons allow electric charge to flow easily through metals, forming a 'sea of electrons' around their fixed nuclei.</p> Signup and view all the answers

<p>Point discharge is the phenomenon where ions are strongly attracted to or repelled from the tip of a charged conductor, leading to ion movement.</p> Signup and view all the answers

<p>Static charges accumulate on the outer surface because like charges repel each other, maximizing their distance apart.</p> Signup and view all the answers

<p>The Van de Graaff generator produces large amounts of static electricity at high voltage to demonstrate various electrostatic phenomena.</p> Signup and view all the answers

<p>The rubber belt carries negative charge from the lower comb to the upper comb, which then builds up positive charge on the dome.</p> Signup and view all the answers

<p>The size of the dome and the quality of the insulating pillars affect the voltage the Van de Graaff generator can generate.</p> Signup and view all the answers

<p>Conductive floor tiles prevent static build-up, reducing the risk of explosive mixtures in the presence of certain anaesthetics.</p> Signup and view all the answers

<p>As the distance between two charges increases, the electrostatic force decreases according to an inverse square relationship.</p> Signup and view all the answers

<p>The permittivity of a medium is inversely proportional to the electrostatic force; lower permittivity results in a stronger force.</p> Signup and view all the answers

<p>Gravitational force is always attractive, while electrostatic force can be either attractive or repulsive.</p> Signup and view all the answers

<p>The permittivity of polystyrene is approximately $3.115 \times 10^{-11}$ F m-1.</p> Signup and view all the answers

<p>The direction of the electrostatic force is along the line joining the two charges, attracting unlike charges and repelling like charges.</p> Signup and view all the answers

<p>Electrostatic precipitation removes suspended particles from smoke by charging the particles and collecting them on oppositely charged plates.</p> Signup and view all the answers

<p>Photocopiers transfer toner to paper using a charged drum, where light alters the charge distribution to create the image.</p> Signup and view all the answers

<p>Personnel are earthed, and sensitive equipment is enclosed in earthed metal containers to prevent static charge accumulation.</p> Signup and view all the answers

<p>Electric field lines are closer together where the electric field is strong and farther apart where the field is weak.</p> Signup and view all the answers

<p>The electrostatic force is calculated using the formula $F = \frac{1}{4\pi \epsilon} \frac{Q_1 Q_2}{d^2}$.</p> Signup and view all the answers

<p>Charge is retained on the outside surface because like charges repel, maximizing distance apart on the dome's exterior.</p> Signup and view all the answers

<p>The point effect facilitates point discharge, which enhances the likelihood of directing a lightning strike safely down the conductor.</p> Signup and view all the answers

<p>A charged object induces opposite charge on the cap, causing like charges to repel and making the gold leaf diverge.</p> Signup and view all the answers

<p>The gold leaf diverges due to repulsion of like charges being induced on the metal rod and gold leaf.</p> Signup and view all the answers

<p>Bring the charged object close to the electroscope's cap and observe the leaf's divergence; an increase indicates the same charge, while a decrease indicates opposite charge.</p> Signup and view all the answers

<p>If the leaf collapses, it indicates that the object is a conductor because charge has flowed into the electroscope.</p> Signup and view all the answers

<p>An electric wind results from point discharge, causing air to move away from the pointed ends of the static spinner's arms.</p> Signup and view all the answers

<p>The electrostatic force is inversely proportional to the square of the distance between the two point charges.</p> Signup and view all the answers

<p>Tall trees can attract lightning strikes, posing a danger as they may not provide safe shelter from a lightning bolt.</p> Signup and view all the answers

<p>Touching the proof plane against the inside of the charged can will not result in charge transfer to the plane, confirming the charge resides on the outside.</p> Signup and view all the answers

<p>In a neutral atom, the number of protons equals the number of electrons.</p> Signup and view all the answers

<p>When two substances are rubbed together, the substance with weaker electron attraction loses electrons to the stronger substance, resulting in charge transfer.</p> Signup and view all the answers

<p>Like charges repel each other, causing the polythene rods to move apart.</p> Signup and view all the answers

<p>An object becomes positively charged when it loses electrons, resulting in an excess of protons.</p> Signup and view all the answers

<p>Unlike charges attract each other due to the electric force generated between them.</p> Signup and view all the answers

<p>The polythene rod becomes negatively charged due to the transfer of electrons from the cloth.</p> Signup and view all the answers

<p>Earthing is crucial to prevent sparks from static electricity, which can ignite flammable vapors and dust.</p> Signup and view all the answers

<p>Metals have free-moving electrons within their lattice structure, allowing electric charge to flow easily.</p> Signup and view all the answers

<p>Point discharge leads to ion movement around the sharp points of a conductor, resulting in a loss of charge.</p> Signup and view all the answers

<p>The generator uses a rubber belt to transfer charge and create high voltage, illustrating principles of static electricity.</p> Signup and view all the answers