Physics

How is the UV wavelength determined?

Ultra Violet light or UV rays is an electromagnetic radiation naturally emitted by the sun. It is also radiated by specially created light like the black light. The UV wave length is shorter than the visible light. A UV wavelength determines how long the wavelength of a particular light is. It is measured in nano meters (nm) or electron volts. The UV wavelength is shorter than that of visible light and hence is not visible to the human eye. The color with the highest frequency that humans can see is violet. Since they cannot see the color of the frequency of this light, hence it is known as the ultra violet light.

The instrument named photodiode is used to measure the UV rays. It converts the UV light into a current. Once converted into a current it can be detected and measured. Then the UV light is expressed in volts. The photocathode is also used to measure the UV rays. This instrument produces electronic emissions when the UV rays fall on it. This is used more for detecting the UV lights than to measure it. There is another instrument to determine the UV wavelength, it is known as the UV detector. The near UV length detectors can detect UV rays in the near 200nm to 400nm range. The Vacuum UV detector has an edge over the others. It can block other sources of light and pick up only UV wavelength.

Wavelength of UV

Uv rays have the wavelength in the range 10 nm to 400 nm, and energies from 3eV to 124 eV.

It is not very easy to determine the UV wavelength. This is because each of these machines picks up all light and not just the UV wavelengths. Thus, the results obtained are not accurate and the aim of the apparatus is lost.. It is extremely difficult to separate normal light from the UV light. UV light is both good and bad for the humans. It is a rich source of vitamin D. At the same time can cause severe sunburn and can cause skin cancer.

How is magnet strength measured?

A magnet is an object which creates a magnetic field around it. The characteristics of the magnet determine the weak to the strong fields of the same around it. Magnets can be categorized into two parts which are as follows:

• Permanent magnets: They are magnetized and would remain magnetized for the lifetime.

• Electro magnets: These are constituted by wire coils and they are befitted with a magnetic field in case electricity runs through it. They lose the magnetic field when the electricity stops.

• Non electro magnets

Measurement of the strength
The strength of the magnet can be measured as its local strength or the magnetic moment. The magnetic moment is calculated on the basis of the substance’s inherent qualities or the magnetism which has been caused as a result of the electric current. In case the substance has an inherent magnetism, the magnitude of each existing elementary particle can be measured effectively. The net moment or the strength can thus be arrived at. In case of passage of an electric current, tracking of the electrons needs to be done to calculate the magnetism of the object.

Magnetometers
The strength of the magnet is usually labeled on all the commercial magnets which are found. The reading is mentioned in terms of the gauss rating. The two types of magnetometers are as follows:

• One of them calculates the net magnetism and is popularly known as scalar device.

• The other tracks the vectors of the magnetic field. Moreover it calculates the strength of the magnetic field in the direction where it is headed towards. It is also known as a vector device.

Each magnometer works in a different way. One should note that that the gauss rating might not show the true reflection of the surface magnetism. The calculation of the magnet strength essentially shows the core strength of the magnet This core strength might be much greater than the surface strength.

How is Electricity Produced?

The principle used to generate electricity came into existence during the late 1820 and the early years of 1830. The principle was discovered by Michael Faraday. The basic method that he invented is still used today. His principle stated that electricity is generated when there is a movement of a loop wire or copper disc between magnet poles.

Electricity is generated by a generator which is known as an electromechanical generator. The generator is driven by engines which work with the help of fuels and nuclear fission. The kinetic energy generated by flowing water or wind is also used for driving these generators.

There are seven different ways in which electricity can be generated. They are as follows:

1. Static electricity: When the charges are separated physically. Examples: Lighting, triboelectric effect.

2. Electromagnetic induction: When the kinetic energy is transformed into the electricity using an electrical generator.

3. Electrochemistry: In this the chemical energy is directly transformed into electricity. For example in case of a battery.

4. Photoelectric effect: The light is transformed into electrical energy. For example solar energy.

5. Thermoelectric effect: When the temperature differences are directly converted into electricity, for example in case of a thermocouple.

6. Piezoelectric effect: Using the mechanical strain of electrical anisotropic crystals.

7. Nuclear transformation: When nuclear energy gets transferred into normal electricity for consumption.

Electricity is an important part of every body’s life. Life would be very difficult without electricity. We should be grateful to the inventor Mr. Michael Faraday who invented electricity. Due to his invention we can live in world brought alive by electricity. For the electricity to be used the first process is to deliver it to the consumers. This process of distribution is done by the power industry.

How is Electrical Resistance Measured?

Electrical resistance is the resistance to the flow of electrical current. This theory was discovered by George Ohm in the 19th century. Resistance is measured in ohms. Electricity is nothing but electrons flowing. In an electrical current, the atoms in the material allow the flow of electrons. If there is poor conductivity it means that the flow of electrons is resisted.

The electrical resistance is actually measured by dividing the voltage by the flow of current in an object. The way the object resists the electrical current depends upon the material.

The flow of current is resisted due to a number of factors:
• The insulation quality
• Impedance of the conductor
• The object density

Electrical resistance is of two types:
1. Direct current ( DC )
2. Alternating current ( AC )

Direct current means that the electric current moves in a unidirectional manner. For example the water that flows out of a garden hose. The water would act like current and the pressure of water will be the voltage. On the other hand the hose would act like a conductor. The hose enables the water to flow in one direction. The wall of the hose provides friction. This then degrades the force of water.
In the case of AC electrical resistance, the only difference in it is that the resistance of electricity flows in different directions.

It is a known fact that any friction creates heat. In the same manner the resistance of electricity will also create heat. If both the friction and resistance are in excess, then the outcome would be dangerous and destructive.

How does sound travel from one place to another?

Sound travel through mechanical waves. These waves are nothing but a disturbance that moves. As they move, they transfer energy from one source to another. Generally the disturbance caused in sound is due to a vibrating object. You hear your own voice because the diaphragm in your throat vibrates.

Medium of sounds
There are various types of mediums through which sound can pass or transferred. These may be interconnected or have their set of interactive particles. Apart from air, sound can also travel through mediums like liquids, gases and solids.

GuitarsSound doesn’t travel through air alone but also via solid surfaces. Try and press your ear against the table. When you tap on the table you can hear the disturbance in the ear. Collision of particles in the table creates sound. These wave moves from one source to another via a process called transmission.

If you consider a bell in the church, then you may notice that the bell rings and vibrates. Basically the bell is flexing inwards and outwards at a rapid pace. During the outward movement particles of air are pushed against the bell and other adjacent air particles. When the bell goes inwards, it also pulls against air particles that are adjacent. This pattern of push and pull is called sound wave. Here the bell is the actual disturbance while air is the medium.

Can everyone hear?
Anything that we hear from the ear is known as sound. The sensations made by sound are heard by the ear. However, not everyone can hear. Persons who have a damaged ear drum lack the hearing sense. Human beings and most animal and bird species have the potential to hear sound. The sound traveling in a medium can only be heard when it reaches the ear. The range of sound can be anywhere between 20 and 20000 hertz.