CAPACITANCE AND MAGNETIC FIELDS Flashcards
What is a capacitor?
A capacitor is an electronic component that stores electrical energy in an electric field. It typically consists of two conductive plates separated by an insulating material called a dielectric.
What are the functions of capacitors in circuits?
Capacitors are used for energy storage, filtering, timing, and smoothing.
What is capacitance?
Capacitance is a measure of a capacitor’s ability to store charge for a given potential difference (voltage) across its plates, defined as C = Q / V.
What is the SI unit of capacitance?
The SI unit of capacitance is the Farad (F), where 1 Farad is defined as one Coulomb of charge stored per Volt of potential difference.
What factors affect the capacitance of a parallel plate capacitor?
The factors include the area of the plates (A), the distance between the plates (d), and the permittivity of the dielectric (ε).
What is the formula for capacitance of a parallel plate capacitor?
C = εA / d = ε₀εrA / d.
What are the types of capacitors?
Types include electrolytic capacitors, ceramic capacitors, film capacitors, and variable capacitors.
What is the energy stored in a capacitor?
A charged capacitor stores electrical potential energy in the electric field between its plates.
What is the formula for the energy stored in a capacitor?
The energy W stored in a capacitor can be expressed as W = 1/2 QV = 1/2 CV² = 1/2 Q²/C.
What is the time constant in a discharging capacitor?
The time constant (τ) is defined as the product of the resistance (R) and the capacitance (C), τ = RC.
What is the definition of a magnetic field?
A magnetic field is a region of space where a magnetic force is exerted on moving electric charges, electric currents, and magnetic materials.
What is magnetic flux density?
Magnetic flux density (B) is a measure of the strength of a magnetic field at a given point.
What is the formula for the force on a current-carrying conductor in a magnetic field?
The force F is given by F = BILsinθ.
What is the Lorentz force?
The Lorentz force is the force experienced by a moving charge in a magnetic field.
What is the formula for the force on a moving charge in a magnetic field?
The force F on a charge q moving with velocity v in a magnetic field B is given by F = Bqvsinθ.
What is the Right-Hand Rule?
Point the fingers of your right hand in the direction of the velocity, curl them towards the direction of the magnetic field. Your thumb will point in the direction of the force on a positive charge. For a negative charge, the force is in the opposite direction.
What happens when a charged particle enters a uniform magnetic field with velocity perpendicular to the field?
The force is always perpendicular to the velocity, acting as a centripetal force, causing the particle to move in a circular path.
The radius of the circular path can be found by equating the magnetic force to the centripetal force: Bqv = mv²/r, which gives r = mv / Bq.
What occurs when the velocity of a charged particle has a component parallel to the magnetic field?
The parallel component remains unchanged, while the perpendicular component causes circular motion, resulting in a helical path.
What are Cathode Ray Tubes (CRTs)?
Devices where electron beams are deflected by magnetic fields to create images on the screen.
How do Mass Spectrometers utilize magnetic fields?
They use magnetic fields to separate ions of different mass-to-charge ratios.
What role do magnetic fields play in Particle Accelerators?
They are used to bend the paths of charged particles, allowing them to be accelerated repeatedly.
How are magnetic fields used in Fusion Reactors?
Magnetic fields are used to confine hot plasma.
What does Oersted’s Experiment demonstrate?
It shows that electric currents produce magnetic fields, as a compass needle is deflected near a current-carrying wire.
What is the magnetic field around a long straight current-carrying wire?
The magnetic field lines form concentric circles around the wire.
The direction can be determined using the right-hand grip rule.
What is the formula for magnetic flux density around a long straight wire?
B = μ₀I / (2πr) where μ₀ is the permeability of free space.
What is the magnetic field due to a current in a circular loop?
It resembles that of a short bar magnet, with a north pole on one side and a south pole on the other.
The direction can be determined using the right-hand rule.
What is the magnetic field inside and outside a solenoid?
A solenoid creates a strong, nearly uniform magnetic field inside and a much weaker field outside.
The direction can be found using the right-hand rule.
What is the formula for magnetic flux density inside a long solenoid?
B = μ₀nI where n is the number of turns per unit length.
What is electromagnetic induction?
It is the phenomenon where an electromotive force (EMF) is induced in a conductor when the magnetic flux through it changes with time.
What is magnetic flux?
It is a measure of the total magnetic field that passes through a given area, given by Φ = BAcosθ.
What is Faraday’s Law of Electromagnetic Induction?
It states that the magnitude of the induced EMF in any closed circuit is equal to the rate of change of the magnetic flux linkage through the circuit.
What does Lenz’s Law state?
The direction of the induced EMF is always such that it opposes the change in magnetic flux that produces it.
What factors affect induced EMF?
Strength of the magnetic field, area of the coil, number of turns in the coil, rate of change of magnetic flux, and orientation of the coil.
What are applications of electromagnetic induction?
Electric generators, transformers, induction cooktops, and metal detectors.
What is the significance of electromagnetic induction?
It is crucial for the generation and distribution of electrical power.
