Electricity
57 flashcards covering Electricity for the MCAT Chem / Phys / Psych / Soc section.
Electricity is the flow of electric charge, typically electrons, through materials like wires or circuits. At its core, it involves concepts such as voltage (the force pushing charges), current (the rate of charge flow), and resistance (opposition to that flow). This topic is fundamental to understanding how energy is generated, transmitted, and used in everyday devices, from batteries to medical equipment, and even in biological processes like nerve impulses.
On the MCAT, electricity features prominently in the Chemical and Physical Foundations section, often through multiple-choice questions testing circuits, Ohm's law, capacitors, and electromagnetic principles. Common traps include confusing series and parallel circuit behaviors or misapplying formulas under time pressure, so pay attention to units and problem contexts. Focus on mastering conceptual applications, like analyzing energy conservation in circuits, to tackle quantitative and qualitative questions effectively.
Practice sketching circuits to solidify your understanding.
Terms (57)
- 01
Electric Charge
Electric charge is a fundamental property of matter that causes it to experience a force in an electric field, existing in two types: positive and negative, and is measured in coulombs.
- 02
Coulomb's Law
Coulomb's law states that the force between two point charges is directly proportional to the product of their charges and inversely proportional to the square of the distance between them.
- 03
Electric Field
An electric field is a region around a charged particle where another charged particle experiences a force, defined as the force per unit charge at a point.
- 04
Electric Field Lines
Electric field lines are imaginary lines that represent the direction of the electric field at various points, originating from positive charges and terminating on negative charges.
- 05
Electric Potential
Electric potential at a point is the electric potential energy per unit charge, measured in volts, and represents the work done per unit charge to bring a test charge from infinity to that point.
- 06
Electric Potential Difference
Electric potential difference, or voltage, is the difference in electric potential between two points, equal to the work done per unit charge to move a charge between them.
- 07
Capacitance
Capacitance is the ability of a system to store electric charge per unit voltage, measured in farads, and depends on the geometry and materials of the capacitor.
- 08
Capacitor
A capacitor is a device that stores electrical energy in an electric field, consisting of two conductors separated by a dielectric, and is used to maintain a potential difference.
- 09
Parallel Plate Capacitor
A parallel plate capacitor consists of two parallel conducting plates separated by a distance, with capacitance given by C = εA/d, where ε is the permittivity, A is the area, and d is the separation.
- 10
Dielectric
A dielectric is an insulating material that increases the capacitance of a capacitor by reducing the electric field between the plates when placed between them.
- 11
Electric Current
Electric current is the flow of electric charge through a conductor, measured in amperes, and is defined as the rate of charge flow per unit time.
- 12
Ohm's Law
Ohm's law states that the current through a conductor is directly proportional to the voltage across it and inversely proportional to its resistance, expressed as V = IR.
- 13
Electrical Resistance
Electrical resistance is a measure of how much a material opposes the flow of electric current, measured in ohms, and depends on the material's resistivity and dimensions.
- 14
Resistivity
Resistivity is a material property that quantifies how strongly it resists electric current, measured in ohm-meters, and is used in the formula R = ρL/A for resistance.
- 15
Conductivity
Conductivity is the reciprocal of resistivity and measures how easily a material allows electric current to flow, with higher values indicating better conductors.
- 16
Series Circuit
In a series circuit, components are connected end-to-end, so the same current flows through all, but the total voltage is the sum of individual voltages.
- 17
Parallel Circuit
In a parallel circuit, components are connected across common points, so the voltage across each is the same, but currents add up.
- 18
Kirchhoff's Voltage Law
Kirchhoff's voltage law states that the sum of all electrical potential differences around any closed loop in a circuit equals zero.
- 19
Kirchhoff's Current Law
Kirchhoff's current law states that the total current entering a junction equals the total current leaving it, conserving charge at nodes.
- 20
Power in Electric Circuits
Power in electric circuits is the rate at which electrical energy is transferred, calculated as P = VI, where V is voltage and I is current.
- 21
Joule Heating
Joule heating is the process where electrical energy is converted to heat due to resistance in a conductor, with energy dissipated as I²Rt.
- 22
Magnetic Field
A magnetic field is a vector field that describes the magnetic influence on moving electric charges, produced by moving charges or magnets.
- 23
Magnetic Force on a Moving Charge
The magnetic force on a moving charge is given by F = q(v × B), where q is charge, v is velocity, and B is magnetic field, perpendicular to both.
- 24
Biot-Savart Law
The Biot-Savart law describes the magnetic field produced by a steady current in a wire, similar to Coulomb's law but for magnetic fields from current elements.
- 25
Ampere's Law
Ampere's law relates the magnetic field around a closed loop to the electric current passing through the loop, stated as ∮B·dl = μ₀Ienclosed.
- 26
Faraday's Law of Induction
Faraday's law states that the electromotive force induced in a circuit is equal to the negative rate of change of magnetic flux through the circuit.
- 27
Lenz's Law
Lenz's law states that the direction of an induced current will oppose the change in magnetic flux that produced it, conserving energy.
- 28
Electromagnetic Induction
Electromagnetic induction is the process of generating an electromotive force by changing magnetic fields, as in generators or transformers.
- 29
Inductance
Inductance is the property of a device that opposes changes in current, measured in henries, and stores energy in a magnetic field.
- 30
Inductor
An inductor is a coil of wire that stores energy in a magnetic field when current flows through it, opposing changes in current.
- 31
RL Circuit
An RL circuit contains a resistor and inductor, where the current grows or decays exponentially with a time constant L/R after a voltage is applied.
- 32
RC Circuit
An RC circuit consists of a resistor and capacitor, where the voltage across the capacitor charges or discharges exponentially with time constant RC.
- 33
Time Constant
The time constant in RC or RL circuits is the time it takes for the current or voltage to reach about 63% of its final value, indicating response speed.
- 34
AC Circuits
AC circuits involve alternating current, where voltage and current vary sinusoidally, requiring concepts like impedance for analysis.
- 35
RMS Value
The root mean square value is the effective value of an alternating current or voltage, used for power calculations as it equals the DC value producing the same power.
- 36
Transformer
A transformer is a device that changes the voltage of an alternating current using electromagnetic induction, with the ratio determined by the number of turns in coils.
- 37
Electric Generator
An electric generator converts mechanical energy into electrical energy through electromagnetic induction by rotating a coil in a magnetic field.
- 38
Electric Motor
An electric motor converts electrical energy into mechanical energy by using the magnetic force on a current-carrying conductor in a magnetic field.
- 39
Gauss's Law
Gauss's law states that the total electric flux through a closed surface is equal to the charge enclosed divided by the permittivity of free space.
- 40
Electric Flux
Electric flux is a measure of the electric field passing through a given area, calculated as the dot product of the electric field and the area vector.
- 41
Conductors in Electrostatics
In electrostatics, conductors have free charges that move to cancel any internal electric field, so the field inside is zero and charges reside on the surface.
- 42
Insulators
Insulators are materials that do not allow charges to move freely, so electric fields can exist within them without charge redistribution.
- 43
Electrostatic Shielding
Electrostatic shielding is the phenomenon where a conductor blocks external electric fields, protecting the interior from electrostatic influences.
- 44
Battery
A battery is a device that provides a constant electromotive force by converting chemical energy into electrical energy.
- 45
Electromotive Force (EMF)
Electromotive force is the voltage provided by a source like a battery, representing the energy per unit charge supplied to move charges around a circuit.
- 46
Internal Resistance
Internal resistance is the opposition to current flow within a battery or source, causing a voltage drop and reducing the terminal voltage.
- 47
Wheatstone Bridge
A Wheatstone bridge is a circuit used to measure unknown resistances by balancing two legs of a bridge circuit until no current flows through the galvanometer.
- 48
Hall Effect
The Hall effect is the production of a voltage difference across an electrical conductor, transverse to an electric current in the conductor and a magnetic field perpendicular to the current.
- 49
Drift Velocity
Drift velocity is the average velocity at which electrons move through a conductor when a potential difference is applied, related to current by I = nqAvd.
- 50
Electron Volt
An electron volt is a unit of energy equal to the energy gained by an electron accelerated through a potential difference of one volt, commonly used in atomic physics.
- 51
Work Done by Electric Field
The work done by an electric field on a charge is the product of the charge and the potential difference, equal to the change in potential energy.
- 52
Energy Stored in a Capacitor
The energy stored in a capacitor is given by U = (1/2)CV², where C is capacitance and V is voltage, representing the electric potential energy in the field.
- 53
Magnetic Dipole Moment
Magnetic dipole moment is a vector quantity for a current loop or magnet, indicating its strength and orientation in a magnetic field, affecting torque and energy.
- 54
Solenoid
A solenoid is a coil of wire that creates a uniform magnetic field inside when current passes through it, similar to a bar magnet.
- 55
Torque on a Current Loop
The torque on a current-carrying loop in a magnetic field is τ = NIAB sinθ, where N is turns, I is current, A is area, B is field, and θ is the angle.
- 56
Cyclotron Motion
Cyclotron motion is the circular path followed by a charged particle moving perpendicular to a uniform magnetic field, with frequency depending on charge and field strength.
- 57
Displacement Current
Displacement current is a term in Ampere's law that accounts for the changing electric field in capacitors, contributing to the magnetic field as if it were a real current.