Physical Quantities

Instructions In the slides that follow, a definition or description of a physical quantity is given. You must name the quantity and state it’s SI units.

This tells how much “stuff” an object is made of. It also provides a measure of an object’s inertia, and determines its gravitational interactions. Mass kg

The force per unit charge that would be experienced by an object at a particular location. Electric Field Newtons per Coulomb OR Volts per meter

The force per unit area exerted on a surface Pressure Pascals

The rate at which charge flows in a wire or circuit Electric Current Amperes

A push or a pullForce Newtons

How tightly matter is packed. Mass per unit volume. Density kg/m 3, g/mL

The amount of charge per volt stored by a device. Capacitance Farads

The amount of energy per unit charge Electric potential (or voltage) Volts

Vector quantity equal to the product of an object’s mass and velocity. Momentum Kg-m/s or N-s

A force acting at a distance that tends to cause a rotation. Torque Newton-meters

The amount of time it takes something to complete one full cycle. Period seconds

Ratio of the speed of light in vacuum to the speed of light in a transparent medium. It determines the refractive (bending) properties of the material. Index of refraction No units

Property that measures how difficult it is for charge to flow in a circuit. Resistance Ohms

The number of magnetic field lines that pass through a surface. Magnetic Flux Webers (or T-m2)

The rate at which an object’s velocity is changing. Acceleration m/s2

The number of oscillations per unit time. Frequency Hertz

A force that acts through a distance. One of the ways of adding or removing energy from an object. Work Joules

The magnitude of an object’s displacement. Distance Meters

Product of a force and the duration of time it is applied. It results in a change of momentum Impulse N-s (or kg m/s)

A vector field that can result in a force if a charged object moves through it. Magnetic Field Tesla

Property of a particle that determines its electrical interactions Electric charge Coulombs

Section II -- Formulas In this section the name or description of a formula is given. You must be able to state the equation and explain what is represented by each letter in the formula.

Newton’s Second Law Fnet=ma or  F=ma

Coulomb’s LawFelec=kq1q2/r2

Faraday’s Law EMF=-N  /  t

Magnetic field due to a long straight wire B=   I/2  r

Ohm’s Law  V=IR

Calculate power in an electric circuit P=IV or P=I 2 R

Variation of resistance with temperature R=R o (1+  T)

Force acting a current carrying wire in a magnetic field. F=BILsin 

Bernoulli’s Law P+  gh+1/2  v 2 =constant

Force acting on a charge in an electric field F=qE

Find the charge stored on a capacitor C=Q/  V

How resistance depends on the geometry of a conductor R=  L/A

Electromotive force created by moving a wire through a magnetic field.  V=EMF=BLv

Snell’s Law n 1 sin  1 =n 2 sin  2

Double slit interference dsin  =n Y n =n L/d

Kinetic friction F f =  k N

Kinematics equation that leaves out time v 2 =v o 2 +2a  x

First law of thermodynamics  U=Q-W (where W is the work done BY the gas)

Universal law of gravity F g =GM 1 M 2 /r 2

Equivalence of mass and energy (used in pair production, pair annihilation and nuclear binding energies). E=mc 2

Capacitors in series1/Ceq=1/C1+1/C2…

How capacitance of a parallel plate capacitor depends on geometry. C=  o A/d

Electric field due to a point charge E=kq/r 2

Force acting on a charge moving through a magnetic field. F=qvBsin 

Impulse momentum theorem F net  t=  p

Wave equation v= f

Lens-mirror formula1/f=1/do + 1/di

Parallel component of an object’s weight on an inclined plane F parallel =mgsin 

Gravitational potential energy on earth (or in a uniform gravity field) Ug=mgh

Spring forceFspring=-kx

Energy of a photonE=hf

Energy levels of hydrogen atom En= eV/n 2

Overall intensity of a blackbody P/A=  T 4

Photoelectric effect q  V=hf-  KE max =hc/ - 

Electric potential in the vicinity of a point charge V=kq/r

Energy of a charge accelerated through a potential difference  E=q  V

Resistors in seriesReq=R1+R2…

Current along parallel branches of an electric circuit I1+I2+I3=Itotal

How to calculate energy used by a device that is in operation for a certain amount of time. Energy=Power x time

Kepler’s Third LawT2/r3=constant

Equation of continuityA 1 v 1 =A 2 v 2

Spring potential energy Uspring=1/2 kx 2

Gravitational potential energy of two spherical masses separated by a distance. Ug= -Gm 1 m 2 /r

Compton scattering  =he/mc(1-cos  )