Chapter21 "physics"

What is the electromagnetic force?

One of the four fundamental forces of nature, affecting charged particles.

What are the two types of electric charge?

Positive and negative.

What happens when two objects with the same electric charge interact?

They repel each other.

What is an ion?

An atom that has gained or lost electrons and thus has a net charge.

What is the SI unit of charge?

Coulomb.

What is the fundamental unit of charge?

1.602 x 10^-19 coulomb, the charge of an electron or proton.

What are conductors?

Materials that allow electric charge to pass through them easily.

What are insulators?

Materials that obstruct the flow of electric charge.

What occurs when a charged rod is brought close to a neutral metallic sphere?

Induction occurs, causing charge separation in the sphere.

What law describes the force between two point charges?

Coulomb's Law.

What is meant by the conservation of electric charge?

Electric charge cannot be created or destroyed, only transferred.

What is the electric field?

A physical quantity that represents the force exerted by a source charge on a test charge.

What happens to the electric field strength when distance from the charge increases?

It decreases with the square of the distance.

What is a dipole?

A system of two equal but opposite electric charges separated by a distance.

What results from a charged object inducing polarization in an insulator?

Partial separation of positive and negative charges.

What characterizes electric field lines?

They indicate the direction and strength of the electric field.

What is the electric dipole moment?

A vector quantity dependent on the charge magnitude and separation distance of a dipole.

What happens to a dipole placed in a uniform electric field?

It experiences no net force but aligns itself along the field.

Define electric potential difference.

The amount of work needed to move a unit charge from one point to another.

What is the principle of superposition in electrostatics?

The net force or electric field due to multiple charges is the vector sum of the individual fields from each charge.

What is the phenomenon of static electricity?

The accumulation of electric charge on the surface of objects.

What is required for electric fields to produce sparks in dry conditions?

A sufficiently strong electric field that can ionize air.

What happens to the electric field within a uniformly charged spherical conductor?

It is zero inside the sphere.

What is an electric field line?

A line that represents the direction and strength of an electric field.

Why can a conductor not harbor excess charge?

Because excess charge flows away to maintain neutrality.

What occurs when metallic objects are grounded?

Excess charge flows to or from the Earth (ground), neutralizing the object.

What do electric fields reflect?

The force that would act on a positive test charge placed in the field.

How does the binding force in an atomic nucleus differ from electrical forces?

It is called the strong nuclear force and does not involve electric charge.

What happens when a charged object is brought near an uncharged object?

The uncharged object can become polarized and attract the charged object.

Explain the statement 'charge can neither be created nor destroyed'.

The total amount of electric charge remains constant over time.

What are free electrons?

Electrons that can move easily within some materials, making them good conductors.

What is the main observable effect of electric fields?

The force they exert on charged objects.

Describe the charge distribution in a dipole.

A dipole has positive and negative charges separated by a distance, creating an electric field.

What is meant by charge induction?

The process where charges are redistributed in a conductor due to an external electric field.

How does Coulomb's law quantify the force between two charges?

The force is proportional to the product of the charges and inversely proportional to the square of the distance between them.

How is charge quantized?

All charges are integral multiples of the fundamental unit of charge.

What defines the direction of the electric field?

The direction of the force that a positive test charge would feel.

What is the relationship between electric field density and electric field strength?

Higher density of field lines indicates a stronger electric field.

What shapes the electric field lines around a positive charge?

They radiate outward from the charge.

Differentiate between conductors and insulators regarding charge movement.

Conductors allow charge to move freely; insulators do not.

Give an example of a good conductor.

Metals such as copper or aluminum.

What is an example of an insulator?

Materials like rubber or glass.

What is the outcome when two dipoles interact?

They exert forces on each other due to their electric fields.

Explain the role of the electric field in a capacitor.

It stores energy by separating charges between two conductive plates.

How does the electric field inside a non-conducting charged sphere behave?

It behaves differently than that of a conducting sphere; it is not zero inside.

What does a spherically symmetric charge distribution produce outside the sphere?

An electric field equivalent to that of a point charge with the same total charge.

Explain the principle of electric field superposition.

The total electric field from multiple sources is the vector sum of the individual fields.

What determines the shape of the electric field lines around multiple charges?

The relative magnitudes and signs of the charges.

Illustrate how objective observation of electric field lines can be achieved experimentally.

Using polarized powders in oil to visualize how they align with electric fields.

How can electric charge be transferred between two objects?

Through contact or induction, as observed in static electricity.

Explain the significance of the electric dipole moment.

It quantifies the strength and orientation of a dipole in an electric field.

What occurs to the electric charge distribution when polarizable materials are placed in an electric field?

They develop an induced dipole as the positive and negative charges separate.

Describe the impact of distance on the electric force between two point charges.

The electric force decreases as the distance between the charges increases.

What is a neutral atom composed of?

Equal numbers of protons and electrons.

What happens when an electric field is applied to an insulating material?

It can cause some polarization of the charges within the material.

What is the electric flux through a closed surface?

It is proportional to the charge enclosed by that surface, as stated by Gauss's Law.

How does gravity compare to electric forces at a fundamental level?

Electric forces can be attractive or repulsive, while gravity is always attractive.

What phenomenon allows for the visual representation of electric fields?

The use of electric field lines.

What is meant by the concept of electric screening?

The reduction of an external electric field within a conductor or dielectric due to induced charges.

Define polarization in the context of electric fields.

The alignment of dipole moments within a material in response to an external electric field.

What occurs at the atomic level during friction-induced static electricity?

Electrons are transferred between materials, resulting in charged objects.

What does the density of electric field lines indicate?

The strength of the electric field at that point.

Describe the behavior of electric field lines in a uniform electric field.

They are parallel and uniformly spaced.

What is Gauss's Law?

A principle relating the electric field through a closed surface to the charge enclosed.

What happens when the distance from a charged sphere increases?

The electric field decreases as the inverse square of the distance.

What notation represents electric dipole moment?

It is often denoted by the symbol p.

What is the effect of charge induction on a conductor?

It allows for temporary charge redistribution without permanent changes.

Why is the electric field inside a conductor zero in electrostatic equilibrium?

Any excess charge resides on the surface and cancels the internal field.

How does Coulomb's law apply to multiple charges?

The net force on any charge is the vector sum of the forces from all other charges.

What property ensures that electric field lines never intersect?

The electric field has a single direction at each point, preventing ambiguity.