E%20=%20mc2

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E mc2
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E mc2 is everywhere!
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E mc2

• Energy (in joules)
• Mass (in kilograms) X
• The Speed of Light Squared
• (in meters squared per second squared)

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The big question???
How much energy will one liter of water yield if
it is converted entirely into energy?
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But Chemistry says matter cannot be created nor
be destroyed???

No its Not! Matter and Energy are two forms of
the same thing!
Neither can be destroyed but, under special
circumstances, either can be turned into the
other
Lots of energy goes into making even a small mass
and it can also be got back in some form.
E mc2 tells you exactly how much energy a given
amount of mass contains.
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The speed of light

• Light travels three hundred million meters in a
  second i.e. 300,000,000 m/s
• So (forgetting the units for now)
• Energy mass x (300,000,000)2
• or E m (90,000,000,000,000,000)
• m (9 x 1016)
• .

Thats a BIG lot
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Mass

• What is the mass of 1 liter of water?
• A liter of water is defined to have a mass of
• one kilogram!
• m 1
• So, E 1 (9 X 1016)
• 9 X 1016 Joules

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What could we do with all this energy?
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Energy Power

• A Joule is the effort required to push one
  kilogram over a meter at an acceleration of one
  meter/second2.
• A Joule expended continuously for one second is a
  Watt.
• A liter of water, converted to energy
• could power a 1 watt light bulb for
• 9x1016 seconds, or 2.5x1013 hours
• or 3 billion years! (2/3 the age of the Earth)

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A 100 Watt bulb

• would only stay lit for 2.5 x 1011 hours!
• There are about 109 families on Earth
• So lets light 109 bulbs of 100 Watt power
• for 250 hours!
• You
• spend the same amount of energy
• as a 100 watt bulb !
• One joule is equal to about four food calories

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The downside
200,000 people have been killed by just 2 atomic
bombs. One Hydrogen Bomb could kill 50 times as
many!
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Most environment friendly application

• All our energy comes from the Sun!
• The Sun has Emc2 as its source of energy.

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Nuclear Fusion

• When 4 hydrogen nuclei are fused together into 1
  helium nucleus, energy is released in the form of
  Light photons and particles called neutrinos. 

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But where does the mass come from?

• Mass of 4 hydrogen nuclei is more than that of 1
  helium nucleus
• So after fusion a little bit of mass is left
  over. This mass deficit appears as the energy of
  light and neutrinos.

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A look inside the sun
The fusion happens 700,000 km deep in the Suns
core. It requires a temperatures of 15 million oC.
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Solar E mc2
The Sun emits 4 x 1026 joules per second

• How much mass does it convert each second in
  order to shine?
• If the Lifetime of the Sun
• is 1010 years, how much mass would it need in
  that time?
• Use m E/c2 !

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How do you convert any mass to Energy on Earth?

• Scientists are trying to make a sun on the Earth
  through fusion reactors that use hydrogen.
• Hydrogen is the simplest lightest element.
• Hydrogen is abundantly found in water!
• Hydrogen fusion has been tried and tested in
  Nature and on Earth (in H-Bombs).

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The only scientist that was able to accomplish
sustained nuclear fusion..
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What are the barriers to attaining nuclear fusion?

• Hydrogen is a diffused gas and it is difficult to
  get its nuclei close enough to fuse.
• They start colliding into each other only at a
  temperature of 15 million degrees C.
• We need to keep it both hot dense.
• A large amount of energy is needed to start the
  reaction and to prevent it from running out of
  control.

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Do it yourself application for Emc2
Solar Lighting
Solar Heater
Solar Cookers