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WorksheetsPHYSICS FINAL
Total questions: 24
Worksheet time: 18mins
Describe what makes a material electrically insulating
variation of index of refraction n with wavelength
holds on to its electrons tightly so that they cannot move from the atoms in response to an electric field
a current carrying loop that occurs naturally when electrons circle atoms
amplify current and were used in long distance telephone communication but now used in logic circuits, computers, etc.
What are the properties of conductors?
E inside is zero
excess charge, if any, resides on surface
just outside E is perpendicular and has magnitude σ/ε0
the electrostatic potential is constant on the surface
E and hence σ is highest at sharp points
What is the significance of 3x10^6 V/m?
speed of light
length of gamma ray
distance to sun
dielectric strength of air
Which property of conductors in electrostatic equilibrium is associated with lightning rods?
E and hence σ are highest at sharp points
E inside is zero
Just outside the surface E is perpendicular and has magnitude σ/ε0
Excess charge if any resides on the surface
the electrostatic potential is constant on the surface
What are the units of energy density and what physical quantity is entirely equivalent to energy density?
J/m^3, weight
J/km^3, pressure
J/m^3, pressure
J/km^3, weight
What law can be used to derive Coulombs law and some of the properties of conductors in electrostatic equilibrium?
Newton's
Gauss'
Coulombs'
Hertz'
What makes a material ferromagnetic?
its ability to steal electrons
unpaired outer electrons form magnetic dipoles around each atom- then you have a quantum mechanical interaction that causes dipoles from nearby atoms to align to form magnetic domains
accelerates from a region of lower electric potentialtoward a region of higher electric potential
its potential energy decreases and its electric potential increases
Faraday's Law
moving magnets (or changing magnetic fields) produce electric fields if a conductor is present current may flow
only a specific amount of an atom's kinetic energy will be lost as the electrons collide with the mercury atom
Whenever there are n-turns of conducting coil in a closed path placed in a time-varying magnetic field, an alternating electromotive force gets induced in each coil.”
The right hand is held with the thumb, index finger and middle finger mutually perpendicular to each other (at right angles), as shown in the diagram. The thumb is pointed in the direction of the motion of the conductor relative to the magnetic field.
List five different practical uses of Faradays law
Properties of conductors in electrostatic equilibrium
list five different practical use of Faradays law
electrical generators
guitar pickups
E-bombs
wireless charging
metal detectors
As a ferromagnet is heated, how does its magnetic properties change with increasing temperature?
decrease in magnetism
increase in magnetism
becomes paramagnetic
becomes diamagnetic
Why does long distance power transmission use high voltages and low currents?
so more power in saved in a generator
to not use energy over long distance
the transmission line has a resistance R by using low currents P=I^2R is minimized
so less power is lost in transmission
which circuit component is Ohmic?
switch
transistor
diode
photodiode
resistor
How does electric current flow through a wire?
it just does
through a series of parallel circuits
a battery produces an electric field in a conductor outermost electrons are accelerated by this field but are bounced backward by those electrons still orbiting the nuclei this transfers energy to atoms as heat
a unit of frequency, measured in s-1, or one over seconds. It is used to measure how many times something happens in a second.
In 1819, Oersted made an important scientific discovery what was it? And what were some of its consequences?
current carrying wires produce magnetic field- led to electromagnets and telegraph
magnet carrying diodes produce electric field- led to television and telegraph
current carrying diodes produce electric field- led to electromagnets and telegraph
heat carrying wires destroy electric field- led to radio and telegraph
What does it mean for a surface to be optically flat
average softness < 1/10 wavelength
average roughness < 1/10 wavelength
highest roughness < 1/100 wavelength
least softness < 1/1000 wavelength
In 1849, Fizeau successfully measured?
speed of radio waves
speed of electron
speed of light
speed of car
Which has more of an effect, the energy carried by an electromagnetic wave or its momentum?
momentum
energy
True or False? Dispersion is the variation of index of refraction n with wavelength
True
False
What is a green flash? And what physical phenomena causes it?
when sun is just about to disappear below the horizon, a flash of green light can sometimes be observed- caused by total internal reflection
when sun is just about to rise above the horizon, a flash of green light can sometimes be observed- caused by dispersion
when sun is just about to disappear below to horizon, a flash of green light can sometimes be observed- caused by total internal reflection
when sun is just about to disappear below the horizon, a flash of green light can sometimes be observed- caused by dispersion
What is total internal reflection and its uses and dangers?
when a beam of light goes from a high index of refraction material to a lower one, beyond some angle light will stay in the material
uses fiber optic objects may not be visible above surface
uses fiber optic objects and is always visible above the surface
when a beam of light goes from a low index of refraction material to a higher one, beyond some angle light will disappear from the material
With regard to electromagnetic waves, what did Hertz do?
disproved Maxwells predictions
verified Marconis predictions
verified Maxwells predictions
disproved Marconis predicitons
With regard to electromagnetic waves, what did Marconi do?
created GPS
created railroads
created telegraph
created commercial radio sets
