Electricity and Magnetism Practice Test

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• A device that increases or decreases the voltage of alternating current?
• Which expression correctly gives the magnetic field inside an ideal solenoid with turns per unit length n and current I?
• In the right-hand rule, the thumb points in the direction of the current. What do the fingers indicate?
• What device converts electrical energy into mechanical energy and can be driven by AC or DC?
• A region in which the magnetic fields of all atoms are lined up in the same direction
• The energy stored in a capacitor with capacitance C and voltage V is:
• In a charging RC circuit, what happens to the capacitor voltage Vc(t) as t becomes very large?
• Speed of light in a medium with refractive index n is which of the following?
• In a plane electromagnetic wave propagating in vacuum, the electric field E, magnetic field B, and the direction of propagation form what kind of set?
• Gauss's law in integral form for electricity is which of the following?
• If a dielectric with dielectric constant κ completely fills the space between the plates of a parallel-plate capacitor, by what factor does the capacitance increase compared to vacuum?
• Capacitance of a spherical capacitor with inner radius a and outer radius b is:
• The Poynting vector S represents which physical quantity?
• Which expression gives the magnetic energy density u_B?
• The electromagnetic wave equation in vacuum for the electric field E is which of the following?
• What is the magnetic energy density for a magnetic field B in vacuum?
• Capacitance per unit length of coaxial cable in vacuum is C' = (2π ε0)/ln(b/a). If the cable length is L, what is the total capacitance?
• Work required to assemble two point charges q1 and q2 separated by distance r from infinity to a fixed separation r equals:
• What describes the area of magnetic force around a magnet?
• A circuit that contains more than one path for current flow is called a
• How does potential energy change with distance for opposite vs like charges?
• What term describes a magnet that is produced by current in a coil with a ferromagnetic core?
• What is the boundary condition for the normal component of the electric displacement D across a boundary with surface free charge σ_free?
• What in a circuit diagram represents a battery?
• A conducting rod of length L moves with velocity v parallel to a uniform magnetic field B. The induced emf is zero because the motion is not perpendicular to B. True or False?
• A coil that has a soft iron core and that acts as a magnet when an electric current is in the coil (solenoid with ferromagnetic core)
• Magnetic field from a finite straight current-carrying wire segment at a distance d is given by which expression?
• For AC circuits, what is the complex impedance of a resistor, an inductor, and a capacitor, and what is the total impedance for series R-L-C?
• What is the continuity equation expressing charge conservation, and its mathematical form?
• The potential difference ΔV between two points equals what integral of the electric field?
• Which device is used to change voltage levels in an alternating current circuit?
• Magnetic field on the axis of a circular loop of radius R carrying current I at a distance z along the axis is given by which expression?
• In a dielectric, what is the relation between the displacement field D, the electric field E, and the polarization P?
• Which of the following expresses the relationship between the electric field E and the electric potential V?
• At a dielectric interface with no surface charge, the tangential components of E satisfy which condition?
• Ampere's law in integral form for steady currents?
• Which statement best describes the right-hand rule for current and magnetic field?
• Unlike charges ________________.
• Faraday's law states that the electromotive force around a closed loop equals what?
• How is the refractive index n related to the material's permittivity and permeability in a non-magnetic medium?
• What is the force on a charged particle due to an electric field called?
• In a series RC circuit with a DC source V0, the voltage across the capacitor as a function of time during charging is:
• What are the 3 ways that electric charge can be transferred?
• Gauss's law for magnetism implies what about magnetic monopoles?
• Which expression gives the energy stored in an inductor of inductance L carrying current I?
• What term describes rapid and interrupted current that changes direction?
• What term describes electrically charged particles flowing in one direction only?
• The impedance Z of a series RLC circuit in phasor form is given by which of the following?
• Gauss's law for magnetism is expressed as which statement?
• Any material that attracts iron or materials containing iron is called a what?
• Which device is used to step up or step down AC voltages in power distribution?
• Which device is used to detect very small electrical currents in a circuit by measuring magnetic deflection?
• Magnetic energy density per unit volume is given by which expression?
• State Snell's law for refraction in terms of media with refractive indices n1 and n2 and incidence and refraction angles θ1 and θ2.
• Which two concepts are connected by the right-hand rule for electromagnetism?
• In an ideal transformer, if the primary turns double while the secondary turns stay the same and the primary voltage is fixed, what happens to the secondary voltage?
• A push or pull exerted by a magnet is called what?
• In AC circuits, the impedance of a capacitor is Z_C = ?
• What is the magnetic force on a straight wire of length L carrying current I in a uniform magnetic field B?
• Doubling the point charge q while keeping distance r fixed changes the electric field magnitude by what factor?
• A straight wire of length L carrying current I is placed in a uniform magnetic field B perpendicular to the wire. What is the magnitude of the magnetic force on the wire?
• What is electricity?
• Which method of charge transfer requires no direct contact?
• According to Faraday's law and Lenz's law, the induced emf will do which of the following with respect to changes in magnetic flux?
• Which machine converts mechanical energy into electrical energy?
• What are the possible charges on a particle?
• What is the Lorentz force on a charged particle with charge q moving with velocity v in electric and magnetic fields E and B?
• What are the common polarization states of an electromagnetic plane wave and how are they defined?
• What is the flow of electric charge called?
• In an RL circuit, the time constant τ is defined by which relation?
• The direction of the electric field produced by a positive point charge is:
• What in a circuit diagram represents a resistor?
• In a coaxial cable with current I on the inner conductor and −I on the outer conductor, what is the magnetic field in the region a < r < b (between the conductors)?
• In a vacuum electromagnetic wave, what is the relation between the magnetic field amplitude B and the electric field amplitude E?
• If the current in a circular loop is doubled while the radius remains fixed, the magnetic field at the center will
• For a rod of length L moving with speed v perpendicular to a uniform magnetic field B, the induced emf is?
• Which statement about motional emf is true?
• If resistance decreases and voltage remains the same, what happens to current?
• What is the torque on a magnetic dipole μ in a uniform magnetic field B?
• Which term denotes the unit used to quantify electrical resistance?
• In a plane electromagnetic wave traveling in the +x direction in vacuum, which of the following is true?
• For an ideal toroid with N turns and mean radius r, which statement correctly describes the magnetic field inside the core?
• Two capacitors C1 and C2 are connected in series; what is the total capacitance C_total?
• Where is Earth's magnetic north pole currently located?
• In a series RLC circuit, under what condition does resonance occur, and what is the impedance at resonance?
• What is the general expression for the speed of an electromagnetic wave in a medium with permittivity ε and permeability μ?
• What is the electric field magnitude at distance r from a point charge q?
• Which device uses an electromagnet to detect small amounts of current?
• What is it called when electric charge is transferred at a distance when objects come in contact with each other's electric fields?
• Which component represents the energy source in a circuit diagram?
• An electric circuit with only one path through which charge can flow is called a
• The tendency for a material to oppose the flow of electrons, measured in ohms, is known as?
• Electric field at distance r from an infinite line charge with linear density λ is given by which expression?
• Gauss's law in integral form is expressed as which of the following?
• A material that conducts electricity well is called what?
• Which of the following describes charging by conduction?
• Which quantity is measured in amperes?
• Which term describes a material in which electrons are not able to move easily?
• Which device converts electrical energy into mechanical energy?
• Which expression correctly relates the speed of light to the vacuum permeability μ0 and the vacuum permittivity ε0?
• Energy stored in an inductor of inductance L carrying current I is given by which expression?
• An RC circuit is discharging through a resistor R with initial capacitor voltage V0. What is Vc(t) as a function of time t?
• What are Maxwell's equations in differential form? List the four equations.
• The differential magnetic field due to a current element at distance r is correctly written as which expression?
• Define the time constant for an RL circuit and give its units.
• In a series RLC circuit, which parameter governs the exponential decay rate of the transient response, and what is the formula?
• What is the boundary condition for the tangential component of the electric field at a perfect conductor surface in electrostatics?
• What is the energy density of the electric and magnetic fields in vacuum?
• What is it called when electric charge is transferred through direct contact?
• How does a good conductor affect an electromagnetic wave, and what is the formula for skin depth?
• If there is no free surface charge at a boundary, what is the relation between the normal components of D on both sides?
• What is the magnetic field at the center of a circular loop of radius R carrying current I?
• For a capacitor with fixed capacitance C, if the charge on the plates is doubled, what happens to the stored energy?
• What term refers to a region in a magnetic material where magnetic moments align in the same direction, contributing to a net magnetic field?
• For a magnetic dipole μ in a uniform field B, the potential energy when μ is parallel to B is which of the following?
• Inserting a dielectric changes the electric field between capacitor plates and the capacitance by what factors (κ = ε_r)?
• Which term describes current that changes direction periodically?
• In a dielectric with relative permittivity ε_r, what is the relation between E inside and E outside for a uniformly filled capacitor?
• Which device melts and opens the circuit when the current becomes too high?
• The potential difference ΔV between two points a and b is defined as:
• Charge that results when an object gains or loses electrons is called what?
• If the magnetic energy density u_B is doubled due to a change in magnetic field, by what factor does u_B increase when B doubles?
• In an inductor, the flux linkage Φ is related to current I by which relation?
• If the current in a long straight wire doubles, what happens to the magnetic field at a fixed distance r?
• What term describes the property that explains attraction or repulsion between poles of magnets?
• If resistance increases while voltage remains constant, what happens to current?
• What is the energy required to assemble a capacitor with final voltage V and capacitance C?
• What is the boundary condition for the tangential component of the magnetic field H across a boundary with a surface current K?
• How does a fuse protect us from circuit overload?
• The magnitude of the electric field produced by a single point charge q at distance r is:
• The capacitance of a parallel-plate capacitor with vacuum, area A, and plate separation d is?
• In the absence of changing electric flux, Ampere's law reduces to which relation?
• Which Maxwell equation in differential form expresses Faraday's law of induction?
• Which expression represents Ampere's law with Maxwell's correction in integral form?
• If the relative permittivity ε_r is used with ε0 to define the permittivity ε, which of the following equals ε?
• Which option correctly describes the reactive part of the series RLC impedance?
• Which principle allows the calculation of the resultant electric field from multiple charges by summing the fields due to each charge individually?
• Which component is essential for creating a magnetic field in devices like electric motors when current passes through it?
• Which statement expresses Kirchhoff's current law (KCL)?
• What in a circuit diagram represents a wire?
• Which statement about the magnetic field of an ideal toroid is true?
• Which term describes current that flows in a single direction?
• What is the magnetic field at the center of a circular loop of radius R carrying current I?
• The ends of a magnetic object, where the magnetic force is strongest, are called what?
• What do electric motors and generators have in common?
• What term describes the region around a magnet where magnetic forces are felt?
• In a dielectric, the displacement field D is related to E by D = ε E, where ε equals ε0 ε_r. Which of the following expresses this relation?
• What polarizations can a plane electromagnetic wave have?
• Biot-Savart law for the magnetic field due to a current element I dℓ is written as which expression?
• Which expression gives Coulomb's law for the force between two point charges, and what are the SI units of the constant k?
• Which component is used to open or close the circuit path?
• In a vacuum, an electromagnetic wave traveling at speed c has a relation between the magnetic field amplitude B and the electric field amplitude E which is which?
• What does Lenz's law state about the direction of the induced current?
• What direction do electrons move in a battery?
• A complete path through which electric charge can flow is called a(n):
• Aurora Borealis is formed in which region of Earth's atmosphere?
• Which expression correctly gives the magnetic energy density in vacuum?
• What is the magnetic field magnitude around a long straight wire carrying current I at distance r, and what is its direction?
• Which component is used to limit current flow in a circuit?
• A region around a charged object where the object's electric force is exerted on other charged objects is called what?
• Inductors in series and in parallel: which statement correctly describes the relationships?
• How is an emf induced in a conducting rod moving with velocity v perpendicular to a uniform magnetic field B (motional emf)?
• Which circuit characteristic allows current to take many paths, so a single path failure does not stop all devices?
• The electric field at a point due to a collection of static point charges is given by:
• The potential difference measured in volts is the amount of work to move a charge from one point to another along a circuit. What is this quantity called?
• In an RL circuit with a DC source Vs, after the switch is closed, the current i(t) evolves toward its steady-state value with a time constant τ = L/R. Which expression correctly represents i(t)?
• creating an electric current by moving magnets which changes the magnetic field
• Lenz's law describes what about the direction of induced currents?
• If you turn off one light and all the lights do not go off, what type of circuit is that?
• Two long parallel wires carry currents in the same direction. What is the direction of the magnetic force between them?
• Which diagram shows all circuit components and how they are connected?
• If a dielectric with relative permittivity ε_r fills the space between the plates of a parallel-plate capacitor, the capacitance changes by what factor?
• State Faraday's law of electromagnetic induction in integral form.
• What is the process of separating positive and negative charge in an object's atoms due to an external electric field?
• In an ideal lossless LC oscillator (no resistance), what is the qualitative behavior of energy exchange between electric and magnetic forms, and what is the period?
• An ideal transformer with turns ratio N1:N2 = 2:1 has secondary current 3 A. What is the primary current?
• The loss of static electricity as charges transfer from one object to another; an example is a lightning strike.
• Gauss's law is especially simple to apply with which symmetry?
• What is the energy density expression for an electromagnetic field in terms of E and B?
• The accumulation of excess electric charge on an object
• In a capacitor, which expression is a correct alternative representation of the energy stored in terms of charge Q and capacitance C?
• A circuit with only one path for current is called a
• Unit of electrical resistance is named what?
• Which statement about μ0, ε0, and the relation c = 1/√(μ0 ε0) is correct?
• Which phenomenon is described by generating a current by moving magnets and changing the magnetic field around a coil?
• In a series RLC circuit, at resonance the impedance is approximately equal to
• What is the speed of light in vacuum in terms of ε0 and μ0?
• An RL circuit with series L and R is connected to a DC source V at t=0. After the switch closes, which expression gives i(t)?
• Which Maxwell equation expresses Gauss's law for magnetism?
• What is the force between two long parallel currents that run in the same direction?
• Inside an ideal solenoid with n turns per unit length and current I, what is the magnetic field?
• Which principle allows you to compute the net electric field at a point by summing fields from multiple charges?
• In a charging RC circuit with a source Vs, the capacitor voltage Vc(t) approaches its final value as t increases. Which expression correctly describes Vc(t)?
• Capacitance of a coaxial cable with length L, inner radius a, outer radius b, in vacuum is:
• What are the SI units of magnetic flux?
• What is it called when electric charge is created by two different materials rubbing together?
• A magnetic dipole μ is placed in a uniform magnetic field B. What is the torque on the dipole, and what is the potential energy?
• What in a circuit diagram represents a light bulb?
• Which term describes a coil of wire that produces a magnetic field when carrying an electric current?
• What is the phenomenon called that is formed in the ionosphere and related to solar wind?
• Which statement about the electric field due to an infinite line charge is true?
• For a finite straight wire segment at distance d with θ1 = 0 and θ2 = π, what is the magnitude of the magnetic field B at that distance?
• Which Maxwell equation in differential form relates the curl of B to current density and the time rate of change of E (the Ampere-Maxwell law)?
• A property of some materials in which there is a force of repulsion or attraction between poles is called what?
• Which statement is true about like charges?
• In a plane electromagnetic wave, the time-averaged energy flux per unit area is which of the following?
• What in a circuit diagram represents a switch?
• Electric potential at distance r from a point charge q located at the origin is:
• Which term refers to a material that conducts electricity well?
• How does the displacement current term in Ampere-Maxwell law help explain charging a capacitor?
• If voltage increases and resistance remains the same, what happens to current?
• What is the work done by the electric field in moving a test charge q from point a to b with potential difference ΔV?
• Define the ideal transformer relations between primary and secondary voltages and currents.
• Which term describes the process by which a charged object can influence another object without direct contact?
• In an AC circuit with R, L, and C, the average power P is P = V_rms I_rms cos φ. Which statement is true for a purely resistive load?
• Which term is used to represent a coil of wire that can create a magnetic field when current flows through it?
• Which statement correctly describes circular polarization?
• What is the Lorentz force on a charge q moving with velocity v in electric field E and magnetic field B?
• If you turn off one light and all the lights go off, what type of circuit is that?
• Capacitance of a parallel-plate capacitor with dielectric constant κ, plate area A, and separation d is:
• Which expression correctly gives the electric energy density in vacuum?
• Which term describes the separation of charges inside an object caused by an external electric field?
• Define the Poynting vector and interpret its physical meaning.
• Like charges ________ each other.
• Which expression represents Snell’s law in terms of refractive indices n1 and n2 for refraction at an interface?
• What is the Biot–Savart law for the magnetic field due to a current element, and how is its direction determined?
• What is the intrinsic impedance of free space Z0, and its approximate value in ohms?
• What is the energy density of an electric field in a dielectric with electric field E and displacement D?
• In a series RLC circuit, at resonance which statement is true?
• What is the physical meaning of the refractive index n in terms of the speed of light in vacuum and in the medium?
• The ends of a magnetic object where the magnetic force is strongest are known as what?
• How do you increase the strength of an electromagnet?
• A device that shows all circuit components and their connections with symbols is called what?
• If the radius R of a single-turn circular loop carrying current I is doubled, the magnetic field at the center becomes what?
• The energy stored in a capacitor of capacitance C charged to voltage V is?