3D2 Electricity & Magnetism Flashcards
Gain understanding of key concepts in electricity and magnetism, including electric charges, fields, and circuits.
What is electricity?
The flow of charge carriers, primarily electrons, through conductors or circuits.
What is charge?
A fundamental property of matter, either positive or negative, which creates electric fields.
Electric fields exert force on other charges within the field, leading to phenomena like attraction and repulsion between charges.
Distinguish between monopoles, dipoles, and quadrupoles.
- Monopoles are single charges.
- Dipoles are pairs of charges.
- Quadrupoles are groups of four charges.
How do electric interactions flow?
From positive charges to negative charges.
Electron flow refers to the movement of electrons from the negative terminal to the positive terminal of a power source.
Conventional current is defined as the flow of positive charge from the positive terminal to the negative terminal of a power source. It is a hypothetical flow that was established before the discovery of the electron and remains in use for the sake of consistency in circuit analysis.
What do electric interactions involve?
Electric fields and electric forces.
What is the relationship between electricity and magnetism?
They are interrelated through electromagnetism, where electric currents generate magnetic fields and vice versa.
What is static electricity?
It occurs when electrons accumulate on a surface or are transferred between bodies without a flow of current.
This can result in phenomena such as sparks or shocks when the accumulated charge is suddenly discharged.
Give examples of static electricity.
- Lightning.
- Rubbing a balloon on hair.
- Static buildup from fuel flow.
How is a magnetic field generated?
When electric charges move.
This movement can be in the form of an electric current in a conductor or the motion of charged particles in space.
What is an electric current?
Tthe flow of charge within a conductor or through a medium.
Describe direct current (DC) and alternating current (AC).
- DC flows continuously in one direction.
- AC alternates direction periodically.
DC is commonly used in batteries and electronics, whereas AC is used in household power supply due to its efficient transmission over long distances.
What is Ohm’s law?
It states that voltage (V) equals current (I) multiplied by resistance (R), V = IR.
Ohm’s law is fundamental in understanding how electrical circuits behave and is used to calculate the values of voltage, current, or resistance in a circuit.
Explain the concept of voltage.
It is electric potential, indicating the difference in charge between two points.
Voltage can be thought of as the “pressure” that pushes electric charges through a conductor.
What is resistance?
It is the measure of a material’s opposition to electric current flow.
The unit of resistance is the ohm (Ω), and it depends on factors like material, temperature, and cross-sectional area.
What is the difference between conductors and insulators?
- Conductors allow electric current to flow easily due to low resistance.
- Insulators resist electric current flow due to high resistance.
Common conductors include metals like copper and aluminum, while common insulators include rubber and glass.
What is electronics?
The study of electrical circuits and devices, including analog and digital systems.
Give examples of electronic devices.
- computers
- smartphones
- household appliances
What are some practical applications of electricity?
- lighting
- heating
- transportation
- medical imaging
- computing
What is Coulomb’s law?
It describes the electrostatic force between two charges, which depends on their magnitudes and separation distance.
How do like and unlike charges interact?
- Like charges repel each other.
- Unlike charges attract each other.
What is an electric circuit?
It is a closed loop through which electric current flows, typically composed of conductors, resistors, and power sources.
Circuits can be simple, like a flashlight, or complex, like a computer motherboard, containing various components that control the flow of electricity.
What is a solenoid?
A coil of wire that generates a magnetic field when an electric current passes through it, commonly used in electromagnets.
Solenoids are used in various applications such as in relays, actuators, and valves where controlled magnetic fields are required.
Define magnetism.
A phenomenon created by the movement of charged particles, such as electrons, which generates a magnetic field.
This movement can be due to the intrinsic spin of electrons or their orbital motion around the nucleus.
Describe how an electromagnet is created.
When an electric current flows through a wire, it generates a magnetic field that disappears when the current stops.
What is ferromagnetism?
It occurs when unpaired electrons in a material align spontaneously, creating a permanent magnetic field, commonly found in metals like iron and cobalt.
What is antiferromagnetism?
It occurs in some solids when ions align in opposite directions, resulting in no net magnetic charge, often observed at low temperatures in metal alloys.
What is ferrimagnetism?
It occurs in some solids, such as metal oxides, when their internal magnetic fields align spontaneously, causing the material to become magnetized.
An example of ferrimagnetic material is magnetite, a type of iron oxide that exhibits strong magnetic properties.
What is paramagnetism?
It occurs when particles within a material align parallel to an external magnetic field, strengthening the field.
Most materials exhibit mild paramagnetism.
Why do opposite magnetic poles attract and like poles repel?
- Opposite poles attract because their opposite charges create a force pulling them together.
- Like poles repel due to their similar charges creating a force pushing them apart.
Can the poles of a magnetic dipole be separated?
No.
If a magnetic dipole is cut into two pieces, each piece will still have both a north and a south pole due to the realignment of charges within the fragments.
How does a compass needle work?
It’s a small magnet that aligns itself with the Earth’s magnetic field, always pointing towards the North Pole.
How does an MRI machine use magnetism?
It uses a strong magnet to align the hydrogen nuclei in the body, then uses radio waves to create images based on the electromagnetic signals from the aligned nuclei.
MRI stands for Magnetic Resonance Imaging, and it is a powerful diagnostic tool in medicine for imaging soft tissues.
