NEW BB Circuits, Magnetism & Induction

What is electrodynamics?

The science of electrical charges in motion, also known as electrical current.

What is electrical current?

The flow of electrons from a high to low potential, following the path of least resistance.

How can current occur in a vacuum?

Electrons jump between two oppositely charged electrodes in a vacuum tube, such as in an X-ray tube.

What happens to ions in gas when oppositely charged electrodes are placed in it?

Positive ions drift towards the negative electrode (cathode) and negative ions drift towards the positive electrode (anode).

What occurs in an ionic solution when salt dissolves in water?

Salt separates into cations (positive ions) that move towards the cathode and anions (negative ions) that move towards the anode.

What is the flow of electrons in a metallic conductor?

Only electrons flow, moving from high electron potential (negative) to low electron potential (positive).

What is polarity in an electric circuit?

The direction of current in a conductor.

What are the three main factors in an electric circuit?

Potential difference (voltage), current (ampere), and resistance (Ohm).

What is potential difference also known as?

Voltage.

What is the unit of voltage?

Volt (V).

What does Ohm's Law state?

Current (I) equals potential difference (V) divided by resistance (R).

What is a dry cell battery?

A battery with a zinc container filled with metallic paste and a central carbon rod, creating a potential difference.

What is a wet cell battery?

A battery containing liquid sulfuric acid with electrodes immersed, causing a chemical reaction.

What is a series circuit?

A circuit with only one path for current to flow.

In a series circuit, how is voltage treated?

Voltage is additive.

In a parallel circuit, how is voltage treated?

Voltage is constant across all branches.

What is the power rule in electrical circuits?

Wattage equals amperage multiplied by voltage (P = IV).

What causes power loss in conductors?

Increased heat energy due to electric current, which raises resistance.

What is the formula for power loss in terms of amperage and resistance?

P = I² X R.

What is the relationship between resistance and the length of a conductor?

Resistance is directly proportional to the length of the conductor.

How does temperature affect the resistance of a conductor?

Resistance increases as temperature rises.

What is the effect of cross-sectional area on resistance?

Resistance is inversely proportional to the cross-sectional area; larger area means less resistance.

What is the significance of a closed circuit?

Current flows only when the switch is closed; an open circuit means the current is interrupted.

What is the formula for calculating voltage using Ohm's Law?

V = I x R.

What is the formula for calculating resistance using Ohm's Law?

R = V / I.

What are the advantages of parallel circuits?

Independent branches prevent other appliances from failing and lower total resistance.

What are the disadvantages of parallel circuits?

Risk of overload from too many branches, which can overheat wiring.

What is the formula to calculate power loss in a circuit?

P = I^2 * R

Given a voltage of 120V and a resistance of 60Ω, what is the current?

I = V/R = 120V / 60Ω = 2A

What is the power loss when the current is 2A and resistance is 60Ω?

P = I^2 * R = (2A)^2 * 60Ω = 240W

What is capacitance?

Capacitance is the amount of energy a capacitor can store.

What is the unit of capacitance?

Farad

What factors determine capacitance?

1. Area of the plate 2. Size of the space between the plates 3. Material of the plate 4. Dielectric used

What is magnetism?

The fundamental property of some forms of matter that has the ability to attract iron, cobalt, and nickel.

What are the units of magnetism?

Tesla or Gauss

What is the relationship between Tesla and Gauss?

1 Tesla = 10,000 Gauss

Name the three types of magnets.

1. Natural magnets 2. Artificial permanent magnets 3. Electromagnets

What is the inverse square law in magnetism?

The force of attraction or repulsion between two magnets varies directly with the strength of the poles and inversely with the square of the distance between them.

What is a magnetic domain?

Any charged particle in motion creates a magnetic field.

What happens to dipoles when acted upon by an external magnetic field?

Dipoles will line up along the magnetic field.

What is magnetic flux?

The lines of force around a magnet that make up a magnetic field.

What is the definition of electromagnetic induction?

The process by which moving magnetic fields produce an electric current.

What does Faraday's Law state?

Whenever a conductor cuts across a magnetic flux, an EMF or potential difference is induced in the conductor.

What is self induction?

The induction of an opposing voltage (EMF) in a single coil of wire carrying a changing current.

What is mutual induction?

The process of inducing an electric current/EMF in a secondary coil by changing the intensity of the magnetic field created by a primary coil.

What is the Left Hand Dynamo Rule?

Index finger indicates direction of flux lines, thumb indicates motion of the conductor, middle finger indicates direction of induced current.

What is an electromagnet?

A temporary magnet that creates a strong magnetic field only when electric current flows through it.

What is a solenoid?

A helix carrying an electric current that concentrates and intensifies the magnetic field lines.

What is the effect of permeability on magnetization?

Higher permeability means easier magnetization.

What is retentivity in magnetism?

How a magnet resists demagnetization.

What is the difference between ferromagnetic, paramagnetic, and diamagnetic materials?

Ferromagnetic materials are strongly attracted to magnets, paramagnetic materials are weakly attracted, and diamagnetic materials are repelled.

What happens to the magnetic field when the current stops flowing?

The magnetic field disappears.

What is the significance of the angle in electromagnetic induction?

As the angle approaches 90 degrees, more flux lines are cut per second, increasing the EMF.

What is the relationship between the number of turns in a coil and EMF?

EMF is directly proportional to the number of turns in a coil.

What is electrostatics?

The study of fixed, or stationary electric charges.

What is a conductor?

Any substance through which electrons can easily flow.

What materials are considered good conductors?

Copper and water (due to salts) are excellent conductors.

What is an insulator?

A substance that inhibits the flow of electrons.

Which materials are good insulators?

Rubber, plastic, glass, and clay.

What is electric current?

The flow of electrons through a conductor.

In how many ways can current occur?

In four ways: vacuum, gas, ionic solution, and metallic conductors.

How does electric current flow in a vacuum?

Electrons can jump a gap between two oppositely charged electrodes.

What happens to ions in a gas when an electric current is applied?

Positive ions drift towards the cathode and negative ions drift towards the anode.

What occurs in an ionic solution when electrodes are immersed?

Positive ions move towards the cathode and negative ions move towards the anode.

What is the main concern in metallic conductors?

Only electrons flow in a metal conductor.

What is the relationship between electron flow and electric current in a conductor?

Electrons move slowly, but the electric current moves at nearly the speed of light.

What is an electric circuit?

A path over which the current flows.

What is electric potential?

The potential to do work due to the electrostatic repulsive force of electrons.

What is the unit of electric potential?

The Volt.

What factors affect resistance in a conductor?

Material, length, cross-sectional area, and temperature.

How does the length of a conductor affect resistance?

Resistance is directly proportional to the length of the conductor.

How does cross-sectional area affect resistance?

Resistance is inversely proportional to the cross-sectional area.

What happens to resistance as temperature increases?

Resistance becomes greater as temperature rises.

What is a dry cell?

A battery with a zinc container and metallic paste, allowing electrons to flow from the rod to the outer edge.

What is a wet cell?

A battery containing sulfuric acid with electrodes immersed in it.

What is the role of a battery in an electric circuit?

To create a potential difference by piling up electrons at one point and removing them at another.

What is the significance of potential difference in an electric circuit?

It represents the amount of work needed to move a unit charge from one point to another.

What is the unit of current?

Ampere, defined as one coulomb per second.

What is the unit of resistance?

Ohm, defined as the resistance of a standard volume of mercury under standard conditions.

What type of current do batteries provide?

Direct current (DC).

What are the essential parts of an elementary electric circuit?

Battery, conductor, and load or resistance.

What is the difference between an open circuit and a closed circuit?

An open circuit is broken at any point, while a closed circuit is complete.

What is the direction of current flow in a circuit supplied by a battery?

From the cathode (-) through the external circuit to the anode (+).

What happens to the current in a series circuit?

The current is constant throughout the circuit.

What is the formula for total resistance in a series circuit?

RT = R1 + R2 + R3 (resistance is added).

What is a parallel circuit?

A circuit that contains elements that bridge rather than lie in a line along the conductor.

What happens to the voltage in a parallel circuit?

Voltage is constant across all components.

What is the formula for total resistance in a parallel circuit?

1/RT = 1/R1 + 1/R2 + 1/R3 (resistance is inversely additive).

What is the purpose of a capacitor?

To store electrical energy without relying on a chemical reaction.

What factors determine the capacitance of a capacitor?

Area of the plates, distance between the plates, material of the plates, and the dielectric used.

What is Ohm's Law?

V = IR, where V is voltage, I is current, and R is resistance.

What is power loss in a circuit?

Power loss is proportional to the square of the current, calculated as P = I²R.

What is the relationship between current and power loss?

Doubling the current results in quadrupling the power loss.

What happens when too many branches are added in a parallel circuit?

The total resistance decreases, and the total amperage increases, which can overload the circuit.

What is the role of a fuse or circuit breaker?

To stop the flow of current when the amperage becomes excessive.

What is a voltmeter used for?

To measure potential difference (voltage) between two points, connected in parallel.

What is an ammeter used for?

To measure current flow per second, connected in series.

What is the effect of resistance on current flow?

Resistance inhibits the flow of electrons in a circuit.

What is the significance of the dielectric in a capacitor?

The dielectric prevents charge from leaking away and affects the capacitance value.

What happens to the current when a circuit is broken?

The current stops flowing.