Energy Forms

1
Energy Forms
2
Energy Classification

• Energy (with the exception of emr) may be
  classified as being either potential energy or
  kinetic energy.

3
Waves

• A wave is a carrier of energy however it does not
  transfer matter.

4
Features of Waves

• Wavelength This is the distance from one crest
  to another crest. It is given the Greek symbol,
  lambda, ?.
• Amplitude This is the distance from the average
  position to the furthest distance a particle will
  move.
• Crest This is the top of a transverse wave.
• Trough This is the bottom of a transverse wave.
• Compression Where all the particles in a
  longitudinal wave are bunched together.
• Rarefaction Where all the particles in a
  longitudinal wave are spread apart.
• Propagation the direction the energy is moving.
• Period the time it takes one wavelength to pass
  a single point.
• Frequency the number of wavelengths that pass a
  point in one second.

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Speed of Waves

• The speed of waves is related to the frequency
  and the wavelength of the wave.
• v f?
• Where v velocity of wave (ms-1)
• f frequency of wave (Hz)
• ? wavelength (m)
• Question 1
• A middle C has a frequency of 256 Hz. What is the
  speed of a sound wave if it has a wavelength of
  1.29 m?
• Question 2
• A surfing wave has a velocity of 2.5 ms-1. If the
  frequency of the wave is 0.13 Hz, what is the
  wavelength of the wave?

6
Experiment Speed of Sound

• Aim To determine the speed of sound.
• Method 1 A distance greater than 100 m was
  measured with a trundle wheel.
• 2 A cap gun was fired at one end of that
  distance and 6 stopwatches were started by
  observers at the other end of the distance when
  they saw the smoke from the gun.
• 3 The stopwatches were stopped by the observers
  when the sound from the cap gun was heard.
• 4 Steps 2 and 3 were repeated 4 times.

7

• Results

8
Light and Mediums

• Light behaves as a wave. When it strikes a new
  medium, it may do one of three things. It may be
• Reflected
• Transmitted
• Absorbed

9
Experiment Angle of Reflection

• Aim To determine the relationship between the
  angle of incidence and the angle of reflection.

Method 1 Shine a single ray of light onto a
mirrored surface and trace the line. Then measure
the angle of incidence and the angle of
reflection. 2 Shine 3 parallel rays of light
onto a mirrored surface and trace the
lines. 3 Shine 3 parallel rays of light onto a
concave mirrored surface and trace the
lines. 4 Shine 3 parallel rays of light onto a
convex mirrored surface and trace the lines.
10
Experiment Angle of Reflection

• Aim To determine the relationship between the
  angle of incidence and the angle of reflection.

Method 1 Shine a single ray of light onto a
mirrored surface and trace the line. Then measure
the angle of incidence and the angle of
reflection. 2 Shine 3 parallel rays of light
onto a mirrored surface and trace the
lines. 3 Shine 3 parallel rays of light onto a
concave mirrored surface and trace the
lines. 4 Shine 3 parallel rays of light onto a
convex mirrored surface and trace the lines.
Results (Leave space for each of the drawings)
Conclusion The angle of incidence and the angle
of reflection are the same. With a concave
surface, this will result in the convergence of
the light to a focal point and beyond that an
inverted image. With a convex surface, this will
result in the divergence of the light.
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Reflection

• Light that is incident upon a surface is
  reflected at the same angle, ?r, as the incident
  angle, ?i.

Most surfaces are not smooth and therefore will
not reflect light so well as a mirror. A piece of
white paper has many bumps on it on a microscopic
level. It will reflect all the light but because
of the bumps, it is reflected at different
angles. The light is said to be scattered.
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Experiment Refraction

• Aim To determine the effect on a wave as it
  travels from one medium to another

Method 1 Shine a ray of light into a rectangular
prism at an angle. 2 Trace the outline of the
rectangular prism and the path the ray of light
takes. 3 Draw in the normal on both sides of the
prism where the light enters the prism and where
it leaves the prism.
Results
Conclusion
13
Transmission

• When light is transmitted from one medium to
  another it slows down. When it is incident at an
  angle then it bends. This is called refraction.
  The degree to which it bends is dependent upon
  the refractive index, n, of the two media.

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When it goes from a lower refractive index to a
higher refractive index, the light bends towards
the normal. When it goes from a higher refractive
index to a lower refractive index, the light
bends away from the normal.
15
Experiment Absorption of Light

• Aim To determine what happens to light energy
  when it is absorbed.

Method 1 Take two identical containers and paint
one black and the other silver. 2 Place an equal
amount of water in each container. 3 Measure the
initial temperature of the water in each
container. 4 Every 10 minutes, measure the
temperature in the water for 1 hr.
Results
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Absorption

• Light that is incident upon an opaque object that
  is not reflected is absorbed. This light energy
  is transferred into heat energy.

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Transparency/Opacity

• Transparent objects allow light to travel through
  so an image is seen clearly.
• Translucent objects disperse the light so that an
  image is not seen clearly.
• Opaque objects do not allow light to travel
  through. It is all reflected.

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Dispersion

• When white light is incident upon a prism, the
  light is split up (dispersed). The spectrum of
  light is ROYGBV (red, orange, yellow, green,
  blue, violet).

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Experiment Series Circuits

• Aim To determine the effect of placing light
  bulbs in series.

Method 1 Set up the circuit as shown. 2 Turn
the power on briefly and measure the current and
the potential difference of the circuit. 3 Place
another light bulb in series and repeat step
2. 4 Place another light bulb in series and
repeat step 3. 5 Measure the current at various
places around the circuit. 6 Measure the
potential difference at various places around the
circuit.
Results
Conclusion
20
Experiment Series Circuits

• Aim To determine the effect of placing light
  bulbs in series.

Method 1 Set up the circuit as shown. 2 Turn
the power on briefly and measure the current and
the potential difference of the circuit. 3 Place
another light bulb in series and repeat step
2. 4 Place another light bulb in series and
repeat step 3. 5 Measure the current at various
places around the circuit. 6 Measure the
potential difference at various places around the
circuit.
Results
Conclusion
21
Experiment Parallel Circuits

• Aim To observe the characteristics and features
  of a parallel circuit.

Method 1 Set up the following circuit as shown
in diagram 1. 2 Measure the current and the
voltage in the places shown. 3 Add a light bulb
as shown in diagram 2. 4 Measure the current and
the voltage in the places shown. 5 Add a light
bulb as shown in diagram 3. 6 Measure the
current and the voltage in the places shown.
Results
Conclusion The voltage is equal in parallel but
the current adds together.
22
Parallel Circuits

• In a parallel circuit, there is more than one
  path for the current to flow. Because of this
  more current can flow. The voltage across each of
  the resistors is the same. The current adds in
  parallel. If one of the circuits breaks, the
  other circuits will still be complete and
  therefore the circuits will work.

23
Experiment Ohms Law

• Aim To determine the relationship between
  current and voltage.

Method 1 Set up a simple circuit involving a
resistor and a voltmeter and an
ammeter. 2 Measure the current when the voltage
is set to the smallest value. Measure the voltage
also. 3 Repeat for different values of the
voltage.
Results
Conclusion
24
Experiment Ohms Law

• Aim To determine the relationship between
  current and voltage.

Method 1 Set up a simple circuit involving a
resistor and a voltmeter and an
ammeter. 2 Measure the current when the voltage
is set to the smallest value. Measure the voltage
also. 3 Repeat for different values of the
voltage.
Results
Conclusion
25
Experiment Ohms Law

• Aim To determine the relationship between
  current and voltage.

Method 1 Set up a simple circuit involving a
resistor and a voltmeter and an
ammeter. 2 Measure the current when the voltage
is set to the smallest value. Measure the voltage
also. 3 Repeat for different values of the
voltage.
Results
Conclusion
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Ohms Law

• Voltage is proportional to current. The factor by
  which it increases is the resistance.
• V IR
• V voltage (V)
• I current (A)
• R resistance (?)

27
Fatty Tanker Einstein

• Einstein, in developing his theory of relativity,
  related the equivalence of mass to energy. Under
  the right conditions, mass can be converted into
  energy and vice versa.
• E mc2
• Where E energy (J)
• m mass (kg)
• c speed of light (3 x 108 ms-1)

28
Nuclear Chain Reactions

• When enough radioactive material is concentrated
  in one spot, the radioactive particles emitted
  can trigger further reactions. This happens
  exponentially and therefore a lot of energy can
  be released at one time.

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Nuclear Power

• Uranium is placed in a chamber. Because the
  Uranium is concentrated, nuclear chain reactions
  occur and give off lots of radiation. The control
  rods are present to slow the reaction down. They
  do this by absorbing extra neutrons. Water is
  circulated in the chamber and heats up. As it
  turns to steam, it is under pressure and thus
  drives a turbine. The turbine allows electricity
  to be generated.

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Experiment Simulation of Steam Turbine

• Aim To simulate a steam turbine

Method 1 The apparatus was set up as
shown. (leave 12 lines) 2 The conical flask was
heated with the Bunsen.
Results The turbine spun around as the steam was
emitted from the glass tubing.
Conclusion The turbine spins because pressure is
built up as the water turns into steam.
31
Turbines

• Electricity can be created from movement in the
  following way. A coil of wire is placed in a
  magnetic field. As the coil of wire rotates, the
  magnetic field causes the electrons to move
  through the coil of wire. Steam or other means
  can be used to turn the coil of wire.

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Gravitational Potential Energy

• Objects attract each other. In reality we are
  only attracted to significantly large objects
  like the Earth. When we jump up, we fall down
  again because of our attraction to the Earth. The
  factors that increase our attraction are the size
  of the two objects and how close they are
  together. The attraction is a force and is
  measured in Newtons.

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Mass and Weight

• Mass is how much of something there is. It is
  measured in kilograms. Weight is how attracted we
  are to something (usually the Earth). It is
  measured in Newtons. On the Earth, our weight is
  our mass multiplied by 9.8.
• W mg
• g 9.8