Each region of the EM spectrum has different uses in everyday life. radio waves These are used for transmitting radio signals, phone signals and television

radio waves have a long wavelength and low energy, this makes them safe for us to use in the way we do, however gamma rays have a short wavelength and high energy, this is what makes them very dangerous.

Task 5

There are eight different types of energy. These are;

Potential energy

This is energy due to position. Potential energy can be found in all labs and work places. For example, beakers on a desk have potential energy, books on shelves have it, and people sitting on chairs also have potential energy.

Kinetic energy

This is energy due to motion, and can be found in many work places. Something that is falling has kinetic energy.

Electrical energy

This is the energy associated with moving electrical charge and can also be found in many work places. For example, the energy that comes from a power socket is electrical energy.

Light energy

This is the energy of electromagnetic waves

Solar energy

This is the energy that is emitted from the sun

Chemical energy

This is the energy released by chemical reactions. This form of energy can be found in a chemistry laboratory

Nuclear energy

This energy is associated with particles of atoms.

Thermal energy.

This is sometimes called heat energy and can be found in many work places and labs. For example, a water bath in a lab will emit heat energy when in use, as will a light bulb in an office.

Different pieces of equipment will use different amounts of energy. For example, a light bulb consumes 75 watts of power, a desk top computer and 15'' monitor consumes 150 watts, a water heater consumes 3800 watts and a power station consumes 500 megawatts of power.

Energy inputs, outputs and efficiencies

A coal fired power station burns coal at a rate of 75kg of coal per second.

Each kg of coal releases 27 million joules of energy

Total input for power station:

Power= work done/ time

Power= 75x27

Power= 2025 mj/s

So the power station produces 2025 million joules of energy per second.

Output= 800 mw

Efficiency= 800/ 2025 x 100

= 39.5%

A water bath in a lab has a power rating of 2.5 kW. It was used to heat tap water at 17(c to a temperature of 37(c for a biology experiment on enzymes. It took 22mins and 45 secs before the water reached the right temperature. The bath contained 30 litres of water

The specific heat capacity of water is 4.2 J kg-1K-1

Total energy used by heating element during the heating period.

Power= 2.5 kW

Time= 22 mins and 45 secs= 1365 seconds

Total energy used (energy output) = 1365x 2.5

= 3412.5 joules

Useful energy absorbed by water

Mass of substance= 30 litres

Specific heat capacity= 4.2 J kg-1 K-1

Temperature rise= 20(c

Energy absorbed= 30x4.2x20

= 2520 Jkg-1K-1

Efficiency= 3412.5/2520 x 100

= 73.8 %

Energy conversions

. Electric fire

Electrical energy --> heat energy, light energy + sound energy

2. A car

Potential energy (petrol) --> kinetic energy, sound energy, + heat energy.

The electric fire is more efficient because the heat energy that it emits is useful. Whereas in most other energy conversions, such as the car, heat energy is actually a waste product and is not used.

Task 6

The microscope is designed to magnify an object/specimen that is placed onto the stage.

A mirror at the bottom of the microscope projects the light through a hole in the stage and through the object. The objective lens picks up this light and magnifies it. The light then continues through the tube to the eye piece, which magnifies the image more before we see it. Most microscopes have more than one objective lens, and these can be changed to increase or decrease the magnification. The objective lens can also be moved closer, or further away from the object to focus it. This is done using the course focus knob. The fine focus knob can also be used to focus the image further. The stage is used to place the object on, and the stage clips to keep the object in place and top it moving around.

PH meters are designed to tell you the pH of a solution quickly and efficiently. They consist of three main parts; the sensing electrode, the referencing electrode and the electronics of the meter

The special glass on the end of the sensing electrode senses H+ ions and a millivoltage is generated. The solution in the bottom of the pH meter that touches the special glass picks up this signal, a pure silver wire dipped in silver chloride passes this signal from the solution to the electrodes cable/connector.

The filling solution in the reference electrode has oH- ions in it. This generates a millivoltage which is passed on in the same way as in the sensing electrode.

The millivoltages are then passed on into the electronic part of the pH meter. The pH meter then takes the inputs from the sensing electrode and the referencing electrode and compares the two values to get a result millivolt reading. The reading in mV is then converted into a pH reading.

In modern pH meters both the sensing electrode and the referencing electrode are contained in one glass tube, with the special glass of the sensing electrode protruding from the bottom.

The light microscope

The purpose of the light microscope is to magnify images. Many factors would have had to be considered when designing this equipment. For example, where the object/specimen would be placed, how the image would be magnified, how we would be able to see the image. These factors are solved by the stage, lenses , eyepiece and built in light sources. Other factors would include, where the microscope would be used, for example, in a teaching lab. This is taken into account by the size of the microscope. It is small enough to sit on the bench of a teaching lab, and relatively inexpensive compared to other microscopes, therefore teaching institutions can afford to purchase more than one for their students.

Bibliography

http://imagine.gsfc.nasa.gov/docs/science/know_1/emspectrum.html

http://www.yesmagbc.ca/how_work/microscope.html

http://www.sensorex.com/support/education/pH_education.html