1. Welcome back to Jeopardy!
Please raise your hand to answer.
An answer must be in the form of a question.
Each correct answer is worth five extra credit points.
The maximum daily score is 25 points.
Each incorrect answer costs five extra credit points.
All negative scores will be cancelled at the end of the game (today).

2. Units are distance divided by time.
What is speed?
This may be calculated as total distance covered divided by the time interval.
What is average speed?
This is always average speed multiplied by time interval.
What is total distance traveled?
This has speed and direction.
What is velocity?

3. Units are velocity divided by time.
What is acceleration?
Motion with a constant downward acceleration of 9.8 m/s2.
What is free fall?
Speed at an instant vs. total distance divided by total time.
What is the difference between instantaneous speed and average speed?

4. Velocity describes both speed and direction.
What is the difference between speed and velocity?
V = at
What is the equation for the speed of an object after time t, starting from rest, due to constant acceleration a?
d = 0.5at2
What is the equation for the distance an object travels during time t, starting from rest, due to constant acceleration a?

5. V = V0 + at.
What is the equation for velocity of an object after time t, starting with speed V0, due to constant acceleration a?
d = V0 t + 0.5at2.
What is the equation for the distance an object travels during time t, starting with initial velocity V0, due to constant acceleration a?

6. In this type of motion, horizontal and vertical components are independent.
What is projectile motion?
First, vertical and horizontal lines are drawn from the tail of the vector. Second, a rectangle is drawn that encloses the vector as its diagonal.
What is vector resolution?
The horizontal velocity is zero, but the vertical velocity decreases 9.8 m/s2.
What is free fall?

7. It has four sides, with opposite sides parallel to each other.
What is a parallelogram?
To find this kind of sum, you need to construct a parallelogram. The sum or resultant is the diagonal.
What is a vector sum?
Satellites in low circular orbit have this speed.
What is 8 km/s?

8. This type of triangle has angles of 37o, 53o and 90o.
What is a 3,4,5 triangle?
In the absence of this, all objects fall with the same acceleration.
What is air resistance?
A projectile must move this fast so that the curve it follows matches the curve of Earth.
What is 8 km/s?
Only this force acts on a high satellite.
What is gravity?

9. He stated that if friction were entirely absent, a ball rolling horizontally would move forever.
Who was Galileo?
This scientist was born in the year Galileo died.
Who was Isaac Newton?
Every object continues in a state of rest, or of motion in a straight line at constant speed, unless it is compelled to change that state by forces acting upon it.

10. What is Newton’s first law, usually called the law of inertia?
The planets would move in straight lines at constant speed.
What would happen if the force of gravity between the sun and planets suddenly disappeared?
An object has little of this if its motion is easily changed.
What is inertia?

11. This is the quantitative measure of inertia. Its unit is the kilogram.
What is mass?
Unlike mass, this quantity varies with height, but it is proportional to mass.
What is weight?
This formula connects weight W, mass m and gravitational acceleration g.
W = mg
Gravitational acceleration g is not constant.
Why does your weight vary with height?

12. Qualitatively, this is a push or a pull, in some direction
Qualitatively, this is a push or a pull, in some direction. Its unit is the Newton (N).
What is a force?
This is the name given to the vector combination of all forces acting on an object.
What is the net force?
This is the condition when net force is zero.
What is equilibrium?
This force cancels your weight when you are motionless.
What is the support force exerted on you?

13. A person with a mass of 50 kg has approximately this much weight.
What is 500 N?
To lose weight without eating less.
Why go to the moon?
V = 6.28 R/T
What is the speed V of an object which moves around a circle of radius R in time T?
A = V2/R
What is the acceleration A of an object which moves around a circle with speed V?

14. The net force (including air resistance) is zero.
When is terminal speed attained?
a = Fnet/m
What is acceleration of an object according to Newton’s second law?
Change in velocity/time
What is acceleration?
P = F/A
What is pressure P due to force F on area A?

15. The acceleration produced by a net force on an object is directly proportional to the magnitude of the net force, is in the same direction as the net force, and is inversely proportional to the mass of the object.
What is Newton’s second law?
It is the mass of an object multiplied by its velocity.
What is the momentum of an object?
Friction or drag that acts on something moving through air.

16. What is air resistance?
Interaction between a baseball and a bat.
What is an example of action and reaction in the game of baseball?
The force of air resistance balances the force of gravity.
When is terminal speed attained?
The cause of acceleration.
What is net force?

17. ~ What is the symbol for “directly proportional to”? Pascal
What is the unit of pressure?
Kilogram divided by (meter times second2).
What is a pascal?
Resultant of all applied forces.
What is meant by the net force on an object?

18. Whenever one object exerts a force on a second object, the second object exerts an equal and opposite force on the first object.
What is Newton’s third law?
The whirling blades are shaped to force air particles downward (action), and the air forces the blades upward (reaction). This upward reaction force is called lift. When lift equal weight of craft, it hovers in midair.
How does a helicopter get its lifting force?

19. It produces a pair of forces, action and reaction, equal in strength and opposite in direction.
What is an interaction between two objects?
It produces a pair of gravitational forces, action and reaction, equal in strength and opposite in direction.
What is a gravitational interaction between two objects?

20. It produces a pair of electrical forces, action and reaction, equal in strength and opposite in direction.
What is an electrical interaction between two objects?
It produces a pair of magnetic forces, action and reaction, equal in strength and opposite in direction.
What is a magnetic interaction between two objects?

21. It is mass times velocity or, in abbreviated notation, mv.
What is momentum?
It is force times time interval or, in abbreviated notation, Ft.
What is impulse?
How is impulse related to momentum change?

22. In the absence of an external force, the momentum of a system remains unchanged.
What is the law of conservation of momentum?
Objects collide without being permanently deformed and without generating heat.
What is an elastic collision?
Colliding objects become tangled or couple together.
What is an inelastic collision?

23. Conservation of momentum and conservation of energy.
What are the two most powerful tools of mechanics?
The momentum before the collision is the same as the momentum after the collision.
What does it mean to say that momentum is conserved in a collision?
It is the quantity force times distance.
What is work?

24. The two things are (1) the application of a force, and (2) the movement of something by that force.
What two things enter into every case where work is done?
The unit of work.
What is a joule?
It is the rate of doing work. It’s unit is known as the watt.
What is power?

25. Kinetic and potential.
What are the two most common forms of mechanical energy?
PE = mgh.
How much potential energy does a mass m have from being lifted a distance h?
KE = 0.5mv2.
How much kinetic energy does a mass m have when its speed is v?
Energy cannot be created or destroyed. It can be transformed from one form to another, but the total amount of energy never changes.

26. What is the law of conservation of energy?
An object does this when it turns around an internal axis.
What is to rotate?
An object does this when it turns around an external axis.
What is to revolve?
An object moving in a circle with constant speed is acted on by this type of force.
What is a centripetal force?

27. This is a fictitious force with a name of its own
This is a fictitious force with a name of its own. For an astronaut rotating in a space laboratory, it can simulate gravity. For a pilot or passenger in projectile motion, it can simulate weightlessness.
What is the centrifugal force?
To gain weight without eating more.
Why go to Jupiter?
This is why when we jump we don’t just keep floating in the air.
What is gravity?

28. This is approximately the acceleration due to gravity.
What is 10 m/s2?
Without this, a ball would roll forever on a horizontal surface.
What is friction?
This quantity has magnitude and direction.
What is a vector?
This quantity has only magnitude.
What is a scalar?

29. A ball rolling off of a table is an example of this.
What is a projectile?
This is a projectile traveling around Earth.
What is a satellite?

30. This property makes wood a good choice for handles on cooking utensils.
What is low heat conductivity?
This is the change of phase from liquid to gas. It takes place at the surface of the liquid.
What is evaporation?
This is a synonym for molecules in the gaseous phase.
What is vapor?
The three common phases of matter.
What are solid, liquid, and gas?

31. When this happens, the temperature on the Celsius scale is said to be 0o.
What is freezing or coexistence of ice and water?
When this happens, the temperature on the Celsius scale is said to be 100o.
What is boiling or coexistence of water and steam?
This produces the sensation of warmth that you feel when you touch a hot surface.

32. What is the transfer of kinetic energy by molecules in the surface to molecules in your fingers?
This is how heat is transferred through metal.
What is conduction?
These materials are the best conductors.
What are materials composed of atoms with “loose” outer electrons?
Heat is energy and is tangible. This is not.
What is cold, or the absence of heat?

33. The quantity that tells how hot or cold something is compared with a standard.
What is temperature?
Nearly all matter does this when temperature increases.
What is thermal expansion?
It shows thermal expansion and contraction of a liquid in a glass tube using a scale.
What is a thermometer?

34. These two properties determine the phase of a substance.
What are temperature and pressure?
In this form of heat transfer, energy moves from one place to another, but molecules do not.
What is conduction?
In this form of heat transfer, molecules of the hotter substance move from one place to another.
What is convection?

35. This property explains why, at a coastline, land warms faster during the day than water.
What is specific heat capacity?
This is the usual wind direction, at a coastline, during the day.
What is a sea breeze, from sea to land?
In the atmosphere, rising air experiences these.
What are expansion and cooling?

36. This is the opposite of evaporation.
What is condensation?
Rising moist air forms these, but rising dry air does not.
What are clouds?
This is basically a cloud that forms near the ground.
What is fog?
Objects in contact at the same temperature.
What is thermal equilibrium?

37. This is the amount of heat required to raise the temperature of one gram of water by one degree Celsius.
What is a calorie?
The units of this property are calories/gram/degree Celsius.
What is specific heat capacity?
All objects emit this in a mixture of wavelengths.
What is radiant energy?

38. Hot bodies emit primarily this kind of radiation.
What is short wavelength radiation?
Cold bodies emit primarily this kind of radiation.
What is long wavelength radiation?
This is the opposite of freezing.
What is melting?
Energy required for freezing or melting.
What is heat of fusion?

39. Energy required for vaporization or condensation.
What is heat of vaporization?
Heat of fusion for water.
What is 80 calories per gram?
Heat of vaporization for water.
What is 540 calories per gram?
Temperature at the bottom of Lake Tahoe.
What is 4o C?

40. Reason the temperature at the bottom of all deep lakes is 4o C.
At what temperature is the density of water greatest?
This adverb describes how boiling point depends on atmospheric pressure.
What is directly?
Best color for maximum radiation absorption.
What is black?
Rate of cooling ~ delta T.

42. This is the study of heat and its transformation into mechanical energy.
What is thermodynamics?
This used to be called “caloric” and flows from hot objects to cold objects.
What is heat?
In this kind of compression or expansion of a system, no heat enters or leaves the system.
What is an adiabatic change?

43. If a cold brick warmed a hot brick, this law would be violated.
What is the second law of thermodynamics?
This is an object which can give up heat or absorb it without change of temperature.
What is a heat reservoir?
This French engineer made a fundamental discovery about heat engines in 1824.
Who was Sadi Carnot?

44. In natural systems, order tends to disorder.
What is the second law of thermodynamics?
This is the measure of disorder.
What is entropy?
Heat added to a system equals the sum of increase in internal energy plus external work done by the system.
What is the first law of thermodynamics?
This is the lowest limit of temperature.
What is absolute zero, or -273o C?

45. By this, we mean any group of atoms, molecules, particles, or objects.
What is a system?
This type of automobile engine has no spark plugs.
What is a diesel engine?
This person invented the diesel engine.
Who was Rudolph Diesel?
Heat flows naturally only in this direction.
What is from hot to cold?

46. When work is done by a heat engine running between two temperatures Thot and Tcold, only some of the input heat at Thot can be converted to work, and the rest is expelled as heat at Tcold.
What is another form of the second law of thermodynamics, applied to heat engines?
This law of thermodynamics is a probability statement.
What is the second law of themodynamics?

47. At this temperature, no more energy can be extracted from a substance and no further lowering of its temperature is possible.
What is absolute zero, or 0 K?
Change in temperature is proportional to change in pressure.
What is the adiabatic form of the first law of thermodynamics?
Chinook winds.
What are westerly, warm, dry winds, at the eastern edge of the Rocky Mountains?

48. Cold, mountain-top air descends and is compressed adiabatically (warmed).
How are chinook winds formed?
Heat will never of itself flow from a cold object to hot object. What, never? Well, hardly ever.
What is the probability interpretation of the second law of thermodynamics?
This is basically a heat engine in reverse.
What is a refrigerator?

49. Of the three common units of temperature, Fahrenheit, Celsius, and Kelvin, these two are equal.
What are Celsius and Kelvin degrees?
Intake, compression, power, and exhaust.
What are the four strokes of an internal combustion engine?
Ten degrees C per kilometer.
How much does the temperature of dry air decrease with increasing altitude?

50. Ideal efficiency of a heat engine.
What is (T2 - T1)/T2?
Actual efficiency of a heat engine.
What is (Q2 - Q1)/Q2?
Physicist’s term for messiness.
What is disorder?
273 K.
What is the freezing point of water?
373 K.
What is the boiling point of water?

51. A vibration.
What is a wiggle in time?
The motion of the medium is at right angles to the direction in which the wave travels.
What is a transverse wave?
The change in frequency of a wave due to the motion of the source or receiver.
What is the Doppler effect?
A region of air with raised pressure.
What is a compression?

52. A region of air with lowered pressure.
What is a rarefaction?
The particles move along the direction of the wave.
What is a longitudinal wave?
In step.
What is another word for in phase?
Wave speed.
What is frequency x wavelength?

53. Unity, non-dimensional.
What is frequency x period?
The V-shaped wave produced by an object moving on a liquid surface faster than the wave speed.
What is a bow wave?
A throbbing variation in loudness when two tones of slightly different frequencies occur together.
What are beats?

54. In equal amplitude waves, this is the sum of trough and crest.
What is cancellation, or destructive interference?
Proper noun for unit of frequency.
What is Hertz?
The positions in a standing wave with largest amplitude.
What are antinodes?
Blue shift.
What is a (Doppler) frequency increase?

55. Pulse of compressed air.
What is a compression?
Back and forth motion of a sound medium.
What are vibrations?
Dramatic increase in amplitude when frequency of forced vibration matches natural frequency.
What is resonance?
Perception of frequency.
What is pitch?

56. Longitudinal waves in air with frequencies below 20 Hertz.
What are infrasonic waves?
Elasticity, size, and shape of the object.
What determines the natural frequencies of an object?
A (Doppler) frequency decrease.
What is a red shift?
Crests.
What is the name for high points in a wave?

57. This occurs when trough overlaps trough, and crest overlaps crest.
What is constructive interference?
Light and radio waves are examples.
What are electromagnetic waves?
An aircraft flying supersonically produces this type of wave.
What is a shock wave?
The time it takes for one back and forth motion.
What is the period of a wave?

58. The distance between successive, identical parts of a wave.
What is wavelength?
It travels through gases, liquids, and solids, but not vacuum.
What is sound?
Longitudinal waves in air with frequencies above 20,000 Hertz.
What are ultrasonic waves?
About 15 times faster than the speed in air.
What is the speed of sound in steel?

59. Length and acceleration due to gravity.
What determines the period of a pendulum?
In waves, these are reciprocal.
What are frequency and period?
These are the stationary parts of a standing wave.
What are nodes?
340 m/s.
What is the speed of sound in air?
1170 ft/s.

60. 20 Hz to 20,000 Hz.
What is the range of hearing for healthy, young adults?
A wiggle in space and time.
What is a wave?
This is the opposite of compression.
What is rarefaction?
This measures and reveals information about waves.
What is an oscilloscope?

61. This is the sound of a cracking whip, or supersonic bullet.
What is a sonic boom?
This term refers to the distance from midpoint of a wave to crest (or trough).
What is amplitude?
This is how often a vibration occurs.
What is frequency?
Light from distant galaxies exhibits this.
What is a red shift?

62. By vibrations of material objects in air.
How are sounds produced?
About four times faster than in air.
How big is the speed of sound in water?
When sound frequency increases, this decreases.
What is sound wavelength?
This product has dimensions m/s.
What is frequency x wavelength?

63. The x-component of this motion is oscillatory, or back and forth.
What is circular motion with constant speed?
The graph of the x-component of this motion is a sine wave.
In this type of motion, matter is not transferred from one place to another.
What is wave motion?

64. Although waves do not carry or transport mass, they do carry this.
What is wave energy?
The back and forth vibratory motion of a swinging pendulum.
What is an example of simple harmonic motion (SHM).
The idealized, back and forth motion of an object dropped into a straight tunnel through the center of Earth.
What is another example of SHM?

65. Both transverse and longitudinal waves can be demonstrated simply by this toy.
What kinds of waves can be demonstrated by a loosely coiled spring, or slinky?
Approximately one millionth the speed of light.
What is the speed of sound in air?
The approximate distance to lightning which is seen three seconds before the sound is heard.
What is one kilometer?

66. The approximate distance to lightning which is seen five seconds before the sound is heard.
What is one mile?
This property of sound is related to loudness.
What is sound intensity?
This property of sound is equal to the square of the sound amplitude.

67. Mathematicians call this a sine curve.
What do you call a graph of simple harmonic motion?
Zero decibels.
What is the threshold of human hearing?
Cycles per second.
What are hertz?
One thousand times greater intensity.
What is a 30 decibel difference between two sounds?

68. “V.”
What is the shape of a bow wave?
Frank Oppenheimer.
Who founded the Exploratorium?
Interference, sometimes constructive, sometimes destructive.
What are beats?

69. Electricity at rest.
What is electrostatics?
An ion.
What is a charged atom?
SI unit of electrical charge.
What is a coulomb?
Because they have some loose electrons.
Why are metals good conductors?

70. The principle that net electric charge is neither created not destroyed but is transferable from one material to another.
What is conservation of electrical charge?
Term applied to an atom or molecule in which the charges are aligned so that one side is slightly more positive or negative than the opposite side.
What is electrically polarized?

71. A material that is a poor conductor of electricity.
What is an insulator?
Electrical potential energy per coulomb at a location in an electric field.
What is electrical potential?
The SI unit of electric potential.
What is a volt?

72. A negatively charged elementary particle.
What is an electron?
A positively charged elementary particle.
What is a proton?
Name for a charged atom.
What is an ion?
Powder monkeys.
What were young boys who ran below the decks of warships to pick up sack of gunpowder for the cannons above?

73. A material that can conduct at some times and insulate at other times.
What is a semiconductor?
Thin layer of semiconducting materials sandwiched together.
What is a transistor?
A material with infinite conductivity.
What is a superconductor?
He proved that lightning is electricity.
Who was Benjamin Franklin?

74. The space around a charge contains this.
What is an electric field?
Electric potential energy divided by charge.
What is electric potential?
Rate of electrical energy transferred by electric current.
What is electrical power?
Amount of current that can kill you if it lasts for more than one second.
What is Amps?

75. Range of resistance the human body offers to the flow of electrical charge.
What is a 100 to 500,000 ohms?
An electrical device that allows current in only one direction.
What is a diode?
Approximate average speed of DC conduction electrons.
What is 0.01 cm/s?
Average speed of AC conduction electrons.
What is 0 cm/s?

76. Approximate speed of a signal in an electrical circuit.
What travels at at little less than the speed of light?
Expression for electrical poer.
What is current times voltage?
One thousand watts.
What is a kilowatt?
A force that may repel or attract.

77. What is the electrostatic force?
Electric current equal voltage divided by resistance.
What is Ohm’s law?
Something that provide an electric potential difference.
What is a voltage source?
Example of a voltage source.
What is a battery or photovoltaic solar collector?

78. A kind of aura that extends through space around an electrical charge.
What is an electric field?
An atom that has lost one or more electrons.
What is a positive ion?
An atom that has gained one or more electrons.
What is a negative ion?
Opposite charges experience this.
What is an electrical force of attraction?

79. The stronger force of gravity and electricity.
What is a electricity?
A satellite is to a planet as an electron is to...
What is a proton?
Two things necessary for an electric current.
What are an electric conductor and an electric potential difference?
Inversely with the square of distance.
How does the electrostatic force between two charges depend on distance between them?

80. Metals.
What are good conductors?
An atom which has no neutrons.
What is hydrogen?
Like charges do this.
What is repel?
A relationship among electrical current, voltage, and resistance.
What is Ohm’s law?

81. The third prong in a power cord.
What is the ground wire?
Direct current.
What is DC?
Alternating current.
What is AC?
The product of current and voltage.
How do you find electrical power?
More massive of electron and proton.
What is an electron?

82. Like charges repel; opposite charges attract.
What is the fundamental rule of electrostatics?
Involuntary muscle contractions (spasms).
What is the effect on the body from a current of 0.01 amps?
Handling a wet hair dryer.
What is like sticking your fingers into a live electrical socket?
The dense, positive atomic core.
What is the nucleus?

83. A complete path for charge flow.
What is a circuit?
Alternate paths for current flow.
What is in parallel?
Electrical elements connected in a row.
What is in series?
Magnet produced by electric current.
What is an electromagnet?

84. A microscopic cluster of atoms with their magnetic fields aligned
What is a magnetic domain?
Every current-carrying wire produces one.
What is a magnetic field?
A compass points in this direction.
What is magnetic north?
Relationship between electric and magnetic fields in an electromagnetic wave.
What is perpendicular?

85. A complete path connecting the positive and negative terminal of a battery.
What is an electric circuit?
Opposite of a generator.
What is a motor?
Term applied to alternate paths between two points of a circuit.
What is in parallel?
Speed of all electromagnetic waves.
What is the speed of light?

86. Voltage induced in a conductor by a changing magnetic field.
What is electromagnetic induction?
Voltage induced in a coil is proportional to the number of loops and to the rate of change of the magnetic field in those loops.
What is Faraday’s Law?
A machine that produces electric current by rotating a coil in a stationary magnetic field.
What is an electric generator?

87. This device uses electromagnetic induction to convert mechanical energy to electric energy.
What is a generator?
In magnetism, these occur in pairs.
What are north and south poles?
This law tells you that if a current-carrying wire produces a force on a magnet, then a magnet must produce a force on a current-carrying wire.
What is Newton’s third law?

88. Just as every coin has two sides, so a magnet has two of these.
What are magnetic north and south poles?
The flow of water in a closed system of pipes.
What does flow of electric charge resemble?
Only this type of circuit allows charge to flow.
What is a closed circuit?
A zigzag line in a schematic diagram.
What is the symbol for electric resistance?

89. In magnetism, these are analogous to charge.
What are magnetic poles?
In magnetism, the interaction rules.
Like poles repel, unlike poles attract?
All bulbs go dark when one burns out.
What happens when one light in a series burns out?
Moving charges are deflected by this field, but without change of energy.
What is the magnetic field?

90. Current times voltage.
What is electric power?
Magnetic declination.
What is the discrepancy between the orientation of a compass and true north?
A useless circuit.
What is a broken circuit?
When your break one of these, you get two, equally strong.
What is a magnet?

91. The space around a magnet, in which a magnetic force is exerted.
What is a magnetic field?
The shape of magnetic field lines around a straight wire.
What are circles?
A simple diagram to represent an electric circuit.
What is a schematic diagram?

92. A useful electric circuit cannot contain these.
What are gaps?
This prevents overloading in circuits.
What is a fuse or circuit breaker?
A way of portraying an electric circuit.
What is a circuit diagram?
The difference between a piece of ordinary iron and an iron magnet.
What are aligned magnetic domains?

93. These are made by placing pieces or iron or certain iron alloys in strong magnetic fields.
What are permanent magnets?
The product divided by the sum.
What is the rule for finding the effective resistance of two resistors in parallel?
Steam, wind, and water are examples.
What provides the mechanical power for an electric generator?

94. They form branches, each with a separate path for flow of charge.
How would you describe a parallel element of an electric circuit?
Any complete path along which charge can flow.
What is an electric circuit?
A linear array of elements, with the same current in each.
What is “connected in series?”

95. If one part of this kind or circuit breaks, then all current ceases.
What is a series circuit?
A device for increasing or decreasing voltage through electromagnetic induction.
What is a transformer?
This fundamental quality underlies the concepts of voltage and current.
What is magnetism?

96. A non-destructive way to stop current flow.
What is “opening a switch?”
The country where Faraday lived.
What is England?
The country where Joseph Henry lived.
What is The United States of America?
He was the first Director of the Smithsonian Institution.
Who was Joseph Henry?

97. Electron path inside a light bulb.
What is the light filament?
Electrical appliances connected one after another.
What is a series circuit?
A device that melts a wire to protect a circuit that would become overloaded.
What is a fuse?
A device that uses bimetallic strips to open a circuit that would become overloaded.
What is a circuit breaker?

98. Danish science professor who discovered the tie between electricity and magnetism.
Who was Hans Christian Oersted?
In this composite circuit element, the effective resistance is less than the resistance of any single resistor.
What is resistors in parallel?
The pattern of compass needles around a current-carrying wire.
What are circles?

99. The person who is credited with discovering the steam engine in 1769.
Who was James Watt?
Where Santa lives.
What is the North Pole?
The most recent time was 700,000 years ago.
When did Earth’s magnetic field reverse?
Next most recent magnetic field reversal?
What happened 870,000 years ago.

100. The product of current times resistance.
How do you calculate the voltage drop across an electrical device?
Like poles repel; unlike poles attract.
What is the basic law of magnetostatics?
The electrons spin in opposite directions, which causes their magnetic fields to cancel.
Why are most substances non-magnetic?
Although it is solid iron, it is too hot.
Why is the Earth’s core non-magnetic?

101. Thank you for playing Jeopardy!