Physics Flashcards
Centripetal Force (F)
= m (v^2 / r)
Points radially inward
Centripetal Acceleration (a)
= v^2 / r
SI Units
Meter, Kilogram, Second, Ampere, Mole, Kelvin and Candela
Vector
Have magnitude and direction
Is displacement vector or scalar?
Vector
Is velocity vector or scalar?
Vector
Is acceleration vector or scalar?
Vector
Is force vector or scalar?
Vector
Scalar
Have magnitude but no direction or dimension
Is speed vector or scalar?
Scalar
Are coefficients of friction vector or scalar?
Scalar
Dot product
Multiplying 2 vectors and resulting in a scalar quantity
= |A| |B| cos (theta)
Cross product
Multiplying 2 vectors and resulting in a vector quantity
= |A| |B| sin (theta)
Static friction (fs)
= 0 < fs < fk
Exists between 2 objects that are not in motion relative to one another
Can take on many values depending on the magnitude of an applied force
Kinetic friction (fk)
= us N
Exists between 2 objects that are in motion relative to one another
A constant value
Coefficient of friction
Depends on the 2 materials in contact
Which is greater: the coefficient of static friction or the coefficient of kinetic friction?
The coefficient of static friction
Newton’s first law (the law of inertia)
F = m a = 0
An object will remain at rest or move with constant velocity if there is no net force acting on it
Newton’s second law
F = m a
Any acceleration is the result of the sum of the forces acting on an object
Newton’s third law
Any 2 objects interacting with one another experience equal and opposite forces as a result of their interaction
Is free fall linear, projectile or circular motion?
Linear
Linear motion
Motion in which the velocity and acceleration are parallel or antiparallel
Projectile motion
Contains x and y components
The only force acting on the object is gravity
Inclined planes
Two dimensional motion
Dimensions are parallel and perpendicular to the surface of the plane
What are the dimensions of circular motion?
Has radial and tangential dimensions
Uniform circular motion
The only force is the centripetal force
No work is done
Potential energy is constant
In which direction does instantaneous velocity point?
Always points tangentially
Translational equilibrium
Occurs in the absence of any new forces acting on an object
The object has constant velocity and/or rotational equilibrium
Rotational equilibrium
Occurs in the absence of any new torques acting on an object
The object has constant angular velocity
Component vectors
x = v cos (theta) y = v sin (theta)
Velocity (v)
= x / t
Universal gravitation equation (F)
= (G m1 m2) / r^2
Acceleration (a)
= v / t
Kinematics (no displacement)
v = vo + (a t)
Kinematics (no final velocity)
x = (vo t) + [(a t^2) / 2]
Kinematics (no time)
v^2 = vo^2 + (2 a x)
Kinematics (no acceleration)
x = v t
Components of gravity on an inclined place
Fg, parallel = m g sin (theta)
Fg, perpendicular = m g cos (theta)
Torque (T)
= r F sin (theta)
Examples of potential energy
Gravitational, electrical, elastic, chemical
Gravitational potential energy (U)
= m g h
Conservative forces
The mechanical energy of the system remains constant
The path the object takes does not matter
Nonconservative forces
The mechanical energy of the system decreases (energy is dissipated)
The path the object takes matters (more energy is dissipated with a longer path)
Is gravity a conservative or nonconservative force?
Conservative
Are electrostatic forces conservative or nonconservative forces?
Conservative
Are elastic forces conservative or nonconservative forces?
Conservative
Is friction a conservative or nonconservative force?
Nonconservative
Is air resistance a conservative or nonconservative force?
Nonconservative
Is viscous drag a conservative or nonconservative force?
Nonconservative
Work (W)
= F d cos (theta)
= P delta V
= delta K
= delta U = q delta V
The dot product of the force and displacement vectors
W = F d cos (theta)
mechanical work
The area under a pressure-volume curve
W = P delta V
isobaric gas-piston system
The work-energy theorem
W = delta K
As the length of an inclined plane increases, what happens to the force required to move an object the same displacement?
As the length of an inclined plane increases, the amount of force necessary to perform the same amount of work (moving the object the same displacement) decreases.
As the effort decreases in a pulley system, what happens to the effort distance to maintain the same work output?
As the effort (required force) decreases in a pulley system, the effort distance increases to generate the same amount of work
What accounts for the difference between work input and work output in a system that operates at less than 100% efficiency?
The decrease in work output is due to nonconservative or external forces that generate or dissipate energy
What does it mean for a device to provide mechanical advantage?
When a device provides mechanical advantage, it decreases the input force required to generate a particular output force. Generally, this is accomplished at the expense of increased distance over which the force must act.
Total mechanical energy
= U + K
The sum of a system’s kinetic and potential energies
What happens if only conservative forces are acting on an object?
The total mechanical energy is conserved
Kinetic energy (K)
= 1/2 m v^2
Elastic potential energy (U)
= 1/2 k x^2
Conservation of mechanical energy (delta E)
= delta U + delta K = 0
Work done by nonconservative forces (W)
= delta E = delta U + delta K
Power (P)
= W / t = delta E / t
Mechanical advantage
= F out / F in
Efficiency
= W out / W in
= [(load) (load distance)] / [(effort) (effort distance)]
Why is there no work done in uniform circular motion?
The displacement vector and force vector are always perpendicular to one another; therefore, no work is done.
Why is potential energy constant in uniform circular motion?
The potential energy does not depend on the position of the object around the circle.
The zeroth law of thermodynamics
When two objects are both in thermal equilibrium with a third object, they are in thermal equilibrium with one another
No heat is flowing
Closed system
Transfers energy
Does not transfer matter
Isolated system
Does not transfer energy or matter
Open system
Transfers both energy and matter
State function
Variables independent of the path taken to achieve a particular equilibrium and are properties of a given system at equilibrium
They may be dependent on one another
Process function
Define the path (or how the system got to its state) through variables
Is heat a process or state function?
Process
Is work a process or state function?
Process
Is pressure a process or state function?
State
Is density a process or state function?
State
Is temperature a process or state function?
State
Is volume a process or state function?
State
Is enthalpy a process or state function?
State
Is internal energy a process or state function?
State
Is Gibbs free energy a process or state function?
State
Is entropy a process or state function?
State
The first law of thermodynamics (conservation of energy)
U = Q - W
In a closed system, the internal energy of a system is equal to the heat put into the system minus the work done by the system
Conduction
Heat exchange by direct molecular interactions
Convection
Heat exchange by fluid movement
Radiation
Heat exchange by electromagnetic waves
Does not depend on matter
What is entropy on a macroscopic level?
The tendency towards disorder
What is entropy statistically?
The measure of the spontaneous dispersal of energy at a specific temperature, increasing the number of available micro states for a given molecule
What is a system’s entropy’s relationship with the system’s surrounding for any thermodynamic process?
The entropy of the system and its surroundings will never decrease; it will always either remain zero or increase.
Specific heat
Heat required to bring the liquid to its boiling point
The amount of energy necessary to raise one gram of substance by one degree Celsius or one kelvin
The specific heat of water
= 1 cal / (g K)
Heat of transformation
During phase change, heat energy causes changes in the particles’ potential energy and energy distribution (entropy), but not kinetic energy
There is no change in temperature
Isothermal processes
The temperature is constant, and the change in internal energy is therefore 0
Adiabatic processes
No heat is exchanged (Q = 0)
Isobaric processes
Pressure is held constant
Isovolumetric (isochoric) processes
The volume is held constant and the work done by or on the system is 0
The second law of thermodynamics
delta S universe = delta S system + delta S surroundings > 0
In a closed system, energy will spontaneously and irreversibly go from being localized to being spread out (dispersed)
Entropy
A measure of how much energy has spread out or how spread out energy has become
Natural process
Irreversible process
Can only be reversible under highly controlled conditions
Fahrenheit (F)
= 9/5 C + 32
Kelvin (K)
= C + 273
Thermal expansion equation (delta L)
= alpha L delta T
Volume expansion equation (delta V)
= beta V delta T
Heat gained or lost (with temperature change) (q)
= m c delta T
Heat gained or lost (phase change) (q)
= m L
Entropy and heat (delta S)
= Q / T
Why does the internal energy increase in an adiabatic compression process?
Q = 0 Compression = work is done on the gas (not by the gas) Therefore, work done by the gas < 0 U = Q - W U = 0 - (- W) U = + W
Heat of fusion
Heat required to melt a solid
Heat of vaporization
Heat required to boil a liquid
How does gauge pressure (P gauge) relate to the pressure exerted by a column of fluid?
Gauge pressure = pressure exerted by a column of fluid + the ambient pressure above the fluid - atmospheric pressure
= P absolute (hydrostatic) - P atmospheric = (Po + p g z) - P atmospheric
Weight of a volume of fluid (Fg)
= density * volume * acceleration due to gravity
= p V g
SI unit for pressure
Pascals (Pa)
Is density a scalar quantity?
Yes
When does gauge pressure = fluid pressure?
When the only pressure above the fluid column is atmospheric pressure
Pressure units
mmHg, torr, atm and Pa
Cohesion
Molecules attaching to one another in a fluid
Give rise to surface tension
Adhesion
Molecules attaching to the container surface containing a fluid
What would the meniscus of a liquid that experiences equal cohesive and adhesive forces look like?
There would be no meniscus and the liquid surface would be flat
A block is fully submerged 3 inches below the surface of a fluid, but is not experiencing any acceleration. What can be said about displaced volume of fluid and the buoyant force?
Displaced volume = volume of the block
Buoyant force = weight of block = weight of fluid displaced
The block and the fluid in which it is immersed must have the same density
To determine the volume of an object by fluid displacement, must the object have a specific gravity greater than 1?
No
A fluid with a low specific gravity can be used instead of water to determine volumes of objects that would otherwise float in water
To which side of a hydraulic lift would the operator usually apply a force: the side with the larger cross-sectional area, to the side with the smaller cross-sectional area?
Smaller cross-sectional area. Because the pressure is the same on both sides of the lift, a smaller force can be applied on the smaller surface area to generate the desired pressure
Dynamic pressure
= 1/2 p v^2
Pressure associated with flow
(like kinetic energy)
Static pressure
Pressure associated with position
like potential energy
Pitot tube
A device that measures static pressure during flow to calculate speed
Viscosity
How thick a fluid is (i.e. the resistance of a fluid to flow)
A measure of the fluid’s internal friction
Laminar flow
Flow in which there are no eddies and in which streamlines roughly parallel each other
Turbulence
The presence of back flow or current eddies
How do the following concepts relate to one another: Venturi effect, Bernoulli’s equation and continuity equation?
Venturi’s effect results from combining Bernoulli’s equation and the continuity equation
What variables does flow rate depend on?
Radius of the tube, pressure gradient, viscosity and length of the tube
What does the continuity equation describe?
The relationship of flow and cross-sectional area in a tube
What does Bernoulli’s equation describe?
The relationship between height, pressure and flow
What does the Venturi effect describe?
The direct relationship between cross-sectional area and pressure
Can the continuity equation be applied to human circulation?
No, due to the presence of pulses, the elasticity of the vessels and the nature of the pressure gradient
Poiseuille’s law can be used for isolated segments
During exhalation, how does the total resistance of the encountered airways change as air leaves the alveoli to escape the nose and mouth?
Total resistance increases as the air exits the body despite the increase in the diameter of the airways. This is because there are fewer airways in parallel with each other.
How does flow in the venae cavae relate to flow in the main pulmonary artery?
In theory, there should be equal flow in the venae cavae and the main pulmonary trunk. In reality, the flow in the venae cavae is actually slightly less than that in the pulmonary trunk because some of the blood entering the right side of the heart is actually from cardiac (coronary) circulation, not systemic circulation.
Density (p)
= m / V
Specific gravity (SG)
= p / (1 g/cm^3)
Pressure (P)
= F / A
Absolute (hydrostatic) pressure (P)
= Po + p g z
= Pressure at the surface of the fluid (usually atmospheric pressure) + pressure due to the fluid itself
The sum of all the pressures at a certain point within a fluid
Pascal’s principle
P = F1 / A1 = F2 / A2 F2 = (F1 A2) / A1
Pressure applied to an incompressible fluid will be distributed undiminished throughout the entire volume of the fluid
Buoyant force (F buoyant)
= p fluid V fluid displaced g = p fluid V submerged g
Poiseuille’s law
Q = (pi r^4 delta P) / (8 nu L)
Q = flow rate r = radius of tube P = pressure nu = fluid viscosity L = length of tube
Determines the rate of laminar flow
Critical speed (vc)
= (Nr nu) / (p D)
Nr = Reynold's number nu = fluid viscosity p = fluid density D = diameter of tube = 2 r, r = radius of tube
Continuity equation (Q)
= v1 A1 = v2 A2
Similar to conservation of mass
Bernoulli’s equation
P1 + 1/2 p v1^2 + p g h1 = P2 + 1/2 p v2^2 + p g h2
(Similar to conservation of energy)
States that the sum of static pressure and dynamic pressure will be constant between any two points in a closed system
Can fluids exert perpendicular forces?
Yes
Can fluids exert shear forces?
No
Is pressure a scalar or vector quantity?
Scalar
In which direction does a gas exert pressure on a container?
Perpendicular direction
Hydraulic machines
Operate based on the application of Pascal’s principle to generate mechanical advantage
Archimedes’ principle
Governs the buoyant force
When an object is placed in a fluid, the fluid generates a buoyant force against the object that is equal to the weight of the fluid displaced by the object
In which direction does the buoyant force point?
Opposite to the direction of gravity
What happens if the maximum buoyant force is larger than the force of gravity on the object?
The object will float (only works if the object is less dense than the fluid)
What happens if the maximum buoyant force is smaller than the force of gravity on the object?
The object will sink (only works if the object is more dense than the fluid)
Viscous drag
Nonconservative force generated by viscosity
When will there be an inverse relationship between pressure and speed (Venturi effect)?
Horizontal flow
When will there be a direct relationship between cross-sectional area and pressure exerted on the walls of the tube (Venturi effect)?
In a closed system
Venturi effect
In horizontal flow, there will be an inverse relationship between pressure and speed
In a closed system, there will be a direct relationship between cross-sectional area and the pressure exerted on the walls of the tube
Is the circulatory system open, closed or isolated?
Closed
Does the circulatory system have constant flow?
No
What happens to resistance as the cross-sectional area increases?
Decreases
What motivates arterial circulation?
The heart
Does venous circulation have higher or lower volume than arterial circulation?
3 times higher
What motivates venous circulation?
Skeletal musculature and expansion of heart
What creates the pressure gradient for the respiratory and circulatory systems?
Inspiration and expiration
What is the air speed in alveoli?
Zero
Why is the speed of blood in the aorta much higher than the speed of blood through a capillary bed?
The cross-sectional area of all the capillaries added together is much greater than the cross-sectional area of the aorta
How does Bernoulli’s equation explain the upward force that permits planes to fly?
The speed of airflow is greater over the curved top of the wing, resulting in less pressure on the top of the wing and the production of a new upward force on the wind, in turn resulting in flight
When placed one meter apart from each other, which will experience a greater acceleration: one coulomb of electrons or one coulomb of protons?
Electrons will experience the greater acceleration because they are subject to the same force as the protons, but have a significantly smaller mass
Is blood a conductor or an insulator?
Conductor
Is hair a conductor or an insulator?
Insulator
Is copper a conductor or an insulator?
Conductor
Is glass a conductor or an insulator?
Insulator
Is iron a conductor or an insulator?
Conductor
Is sulfuric acid a conductor or an insulator?
Conductor
Is distilled water a conductor or an insulator?
Insulator
What is the electric field midway between two negative charges in isolation?
The electric field would be zero because the two charges are the same. In this cases, the fields exerted by each charge at the midpoint will cancel out and there will be no electric field.
What direction does a negative electrostatic force point?
Towards the source charge (because we use the perspective of a small positive test charge)
What direction does a positive electrostatic force point?
Away from the source charge (because we use the perspective of a small positive test charge)
How do distance and charge relate to electrostatic force?
Electrostatic force is directly related to the charge and related to distance by an inverse square relationship
How do distance and charge relate to electric field?
Electric field is unrelated to test charge but is still related to distance by an inverse square relationship
What creates the electric field: test charge or source charge?
Source charge
How does a change in electrical potential energy from -4 J to -7 J reflect on the stability of a system?
The system has become more stable
The relationship between electrical potential energy and Coulomb’s law
Electric potential energy is Coulomb’s law multiplied by distance
The relationship between gravitational potential energy and the universal law of gravitation
Gravitational potential energy is the universal law of gravitation multiplies by distance
How does electrical potential energy change between two particles as the distance between them increases?
If both particles have the same charge, the electric potential energy decreases and distance increases. If the two particles have opposite charges, then the electrical potential energy increases as distance increases.
Electrical potential
The ratio of a charge’s electrical potential energy to the magnitude of the charge itself
Voltage (potential difference)
A measure of the change in electrical potential between two points, which provides an indication of the tendency towards movement of a test charge in one direction or the other
How will a charge that is placed at a point of zero electrical potential move relative to a source charge?
A charge will move in such a way to minimize its potential energy. Placing a charge at a point of zero electrical potential does not indicate that there is zero potential difference, so the charge may or may not move (and if it moves, it may move towards or away from the source depending on the sign of the source charge and the test charge).
Are the units of electrical potential energy, electrical potential, potential difference (voltage) different?
Yes, electrical potential energy is in joules, while electrical potential and potential difference (voltage) are in volts
Equipotential lines
The sets of points within space at which the potential difference between any two points is zero (i.e. they have the same electric potential). This is best visualized as concentric spheres surrounding a source charge.
Electric dipole
The separation of charge within a molecule such that there is a permanent or temporary region of equal and opposite charges at a particular distance
What is the voltage between two points on an equipotential line? Will this voltage cause a charge to move along the line?
There is no voltage between two points on an equipotential line, so there will be no acceleration along the line. However, there is a potential difference between different sets of equipotential lines, which can cause particles to move and accelerate.
Why is the electrical potential at points along the perpendicular bisector of a dipole 0?
The perpendicular bisector of an electric dipole is an equipotential plane that is perpendicular to the axis of the dipole. As such, the equation V = [(k q d) / r^2] cos (theta) is necessarily equal to 0 because cos 90 = 0
What is the behavior of an electric dipole when exposed to an external electric field?
A dipole will rotate within an external field such that its dipole moment aligns with the field (angle between dipole and field is 0 degrees)
What are the requirements to have a nonzero electric field?
Charge
What are the requirements to have a nonzero magnetic field?
Moving charge
What are the requirements to have a nonzero magnetic force?
External field acting on a charge moving in any direction except parallel or antiparallel to the external field
Which would experience a larger magnetic field: an object placed five meters to the left of a current carrying wire, or an object placed at the center of a circle with a radius of five meters?
The magnetic field created by the current-carrying wires is B = (uo I) / (2 pi r)
The magnetic field created by the loop of wire is B = (uo I) / (2 r)
The magnetic field at the center of the loop must be larger because the denominator in that equation does not include pi
Cross product right hand rule
Index in the direction of velocity
Palm in the direction of magnetic field
Thumb in the direction of force
What is the direction of force if velocity points up the page, magnetic field points to the left and the particle is an electron?
Into the page
What is the direction of force if velocity points into the page, magnetic field points out of the page and the particle is a proton?
None, sin 180 = 0
What is the direction of force if velocity points to the right, magnetic field points into the page and the particle is a Proton?
Up the page
What is the direction of force if velocity points out of the page, magnetic field points to the left and the particle is an electron?
Up the page
What is the direction of force if velocity points down the page, magnetic field points to the right and the particle is a neutron?
None, q = 0
Coulomb’s law
Fe = (k q1 q2) / r^2
Give the magnitude of the electrostatic force vector between two charges
Electric field (E)
= Fe / q = (k Q) / r^2
The ratio of the force that is exerted on a test charge to the magnitude of that charge
Electric potential energy (U)
= (k Q q) / r
The amount of work required to bring the test charge from infinitely far away to a given position in the vicinity of a source charge
Electric potential (from electrical potential energy) (V)
= U / q
Electric potential (from source charge) (V)
= (k Q) / r
Voltage equation (delta V)
= Vb - Va = Wab / q
Electrical potential near a dipole (V)
= [(k q d) / r^2] cos (theta)
Dipole moment (p)
= q d
Electric field on the perpendicular bisector of a dipole (E)
= [1 / (4 pi epsilon o)] (p / r^3)
Torque on a dipole in an electric field (T)
= p E sin (theta)
Magnetic field from a straight wire (B)
= (uo I) / (2 pi r)
Magnetic field from a loop of wire (B)
= (uo I) / (2 r)
Magnetic force on a moving point charge (Fb)
= q v B sin (theta)
Magnetic force on a current-carrying wire (Fb)
= I L B sin (theta)
SI unit for charge
Coulomb
Charge on a proton and an electron
1.60e-19 C
Conductor
Allow the free and uniform passage of electrons when charged
Insulators
Resist movement of charge and will have localized areas of charge that do not distribute over the surface of the material
Where does the electrostatic force vector point?
Along the line connecting the centers of the two charges
Does every charge generate an electric field?
Yes
Can the electric field exert forces on other charges?
Yes
Field lines
Represent electric field vectors
Radiate outward from positive source charges
Radiate inward towards negative source charges
In which direction does a positive test charge move?
In the direction of field lines
In which direction does a negative test charge move?
In the opposite direction of field lines
How does the electrical potential energy of a system increase?
When two unlike charges move away from each other or when two like charges move towards each other
How does the electrical potential energy of a system decrease?
When two unlike charges move towards each other or when two like charges move further apart
Do different points in the space of an electric field surrounding a source charge have different electrical potential values?
Yes
Is voltage path dependent?
No
Is voltage a state or process function?
State
In which direction do positive test charges move?
High potential to low potential
In which direction do negative test charges move>
Low potential to high potential
In which direction to equipotential lines point?
Perpendicular to electric field lines
Is work done when a charge is moved from one equipotential line to another?
Yes, but it is independent of the pathway taken between the lines
Is work done when a charge moves from one point to another on the same equipotential line?
No
How is an electric dipole generated?
Two charges of opposite signs are separated by a fixed distance d
Will a dipole experience a net torque in an external electric field?
Yes, until it is aligned with the field
How are magnetic fields created?
Magnets and moving charges
SI unit for magnetic field
Tesla
Diamagnetic materials
Do not possess unpaired electrons and are slightly repelled by a magnet
Paramagnetic materials
Possess unpaired electrons and become weakly magnetic in an external magnetic field
Ferromagnetic materials
Possess unpaired electrons and become strongly magnetic in an external magnetic field
In which direction do field lines in magnets point?
From the North Pole to the South Pole
Magnetic fields in current-carrying wires
Concentric circles surrounding the wire
When do point charges undergo uniform circular motion?
In uniform magnetic fields, wherein the centripetal force is the magnetic force acing on the point charge
Lorentz force
The sum of the electrostatic and magnetic forces acting on a body
Magnetic field right hand rule
Thumb tangent to circle in direction of charge motion
Curled fingers in direction of magnetic field
A dipole is placed in an electric field and is allowed to come to equilibrium. Why does the dipole experience no rotational or linear movement when the direction of the electric field is suddenly reversed?
Torque is a function of both force applied and the angle at which it is applied. A dipole placed in an electric field will experience a torque until it comes to rest oriented within the field, at which point the angle between the plane of the dipole and the electric field is 0 degrees. Once this point if reached, inverting the electric field has no impact on the dipole because it will now have an angle of 180 degrees, the sine of which is still 0. Note, however, that is is an unstable setup; any deviation in the dipole from its rest position will immediately result in torque on the dipole and force it to realign with the new field.
Current
The movement of positive charge through a conductive material over time from the high-potential end to the low-potential end
Voltage
A potential difference between two points
Electromotive force (emf)
The potential difference of the voltage source for a circuit, usually a battery
Conductivity
The reciprocal of resistance and is a measure of permissiveness to current flow
In a circuit, are the number of electrons entering a point and leaving that point the same?
Yes
Is the sum of voltage sources in a circuit always equal to the sum of voltage drops in that circuit?
No
Current unit
Amperes = C / s
Amperes
= C / s
Voltage unit
Volts = J / C
Volts
= J / C
Electromotive force (emf) unit
Volts = J / C
Conductivity unit
Siemens (S)
Kirchhoff’s junction rule
The number of electrons (currents) entering a point and leaving that same point are the same
I into junction = I leaving junction
How does adding a resistor in series affect the total resistance of a circuit that has resistors in series?
Increase total resistance
How does adding a resistor in parallel affect the total resistance of a circuit that has resistors in series?
Decrease total resistance
What four physical quantities determine the resistance of resistor?
Resistivity, length, cross-sectional area and temperature
How does power relate to current, voltage and resistance?
P = I V = I^2 R = V^2 / R
Will the internal resistance of a battery lower the amount of current it can provide?
Yes
The internal resistance will lower the available voltage for the circuit. Lowering the available voltage will also lower current for any given resistance.
How does removing a resistor in series affect the total resistance of a circuit that has resistors in series?
Decrease total resistance
How does adding a resistor in series affect the total resistance of a circuit that has resistors in series?
Increase total resistance
Assuming the plates are attached by a conductive material, how does a capacitor behave after the voltage source has been removed from a circuit?
The capacitor discharges, proving a current in the opposite direction of the initial current
How does a dielectric material impact capacitance?
Increase capacitance
How does a dielectric material impact voltage?
Decrease voltage if the capacitor is isolated when the dielectric is introduced
Constant voltage if the capacitor is in a circuit when the dielectric is introduced because it is dictated by the voltage source
How does a dielectric material impact charge?
If the capacitor is isolated, the stored charge will remain constant because there is no additional source of charge
If the capacitor is in a circuit, the stored charge will increase
How does adding a capacitor in series affect the total capacitance of a circuit that has capacitors in series?
Decrease total capacitance
How does removing a capacitor in series affect the total capacitance of a circuit that has capacitors in series?
Increase total capacitance
How does adding a capacitor in parallel affect the total capacitance of a circuit that has capacitors in series?
Increase total capacitance
How does removing a capacitor in parallel affect the total capacitance of a circuit that has capacitors in series?
Decrease total capacitance
What physical qualities contribute to the capacitance of a capacitor?
Surface area, distance and dielectric constant
What does an ammeter measure?
Current
Where is an ammeter placed?
In series with the point of interest
What is the ideal resistance for an accurate ammeter reading?
0
What does a voltmeter measure?
Voltage drop (potential difference)
Where is a voltmeter placed?
Parallel with circuit element of interest
What is the ideal resistance for an accurate voltmeter reading?
Infinit amount
What does an ohmmeter measure?
Resistance
Where is an ohmmeter placed?
Two points in series with circuit element of interest
Inserted around a resistive element to measure resistance
Self-powered
What is the ideal resistance for an accurate voltmeter reading?
0
Should a voltmeter and an ammeter be placed in the same circuit?
They can be
Voltmeters and ammeters are designed to have minimum impact on a circuit, thus they can be used together
Current (I)
= Q / delta t
Kirchhoff’s loop rule
V source = V drop
In a closed loop, the sum of voltage sources is always equal to the sum of voltage drops
Resistance (R)
= (p L) / A
The opposition to the movement of electrons through a material
Ohm’s law
V = I R
For a given resistance, the magnitude of the current through a resistor is proportional to the voltage drop across the resistor
Voltage and cell emf (V)
= E cell - (I r internal)
Electric power (P)
= IV = I^2 R = V^2 / R
Voltage drop across circuit elements (series)
V total = V1 + V2 + …
Equivalent resistance (series)
R total = R1 + R2 + …
Voltage drop across circuit elements (parallel)
V total = V1 = V2 = …
Equivalent resistance (parallel)
1 / R total = (1 / R1) + (1 / R2) + …
Capacitance (C)
= Q / V
Capacitance based on parallel plate geometry
C = epsilon o (A / d)
In parallel plate capacitors, capacitance is determined by the area of the places and the distance between the plates
Electric field in a capacitor (E)
= V / d
Potential energy of a capacitor (U)
= 1/2 CV^2
