Does a Fluorescent lamp contain any poisonous Chemical? How can I clean it up in case it breaks in my home?

Fluorescent light tubes or Compact Fluorescent Light bulbs are known to glow brightly, there light is usually like that of a day light and they use less energy compared to filament light bulbs. With compact fluorescent light bulbs in service, the rate at which bulbs are changed reduces! So this can help save money. 
Besides their inner surfaces being coated with a fluorescent, fluorescent light tubes are filled with low pressure Mercury vapor and other gases which enable it to produce bright light. Mercury is a very poisonous chemical which should be handled with care.

Compact fluorescent light CFL bulb/tube.

In case a fluorescent tube or a CFL is broken, the following safety measures should be taken into consideration:

• Everybody should leave the room, when this has happened in doors.
• Let there be an air flow in the room, for 10 to 15 minutes by opening a window and a door.
• Switch off, if any, the air conditioning system.
• Collect materials needed to clean up broken bulb:
• stiff paper or cardboard
• damp paper towels or disposable wet wipes
• sticky tape
• rubber gloves
•  a sealable plastic bag or container.

Start the cleanup

•  Put on rubber gloves and scoop up glass fragments and powder using a cardboard or a stiff paper. Place them in a sealable container or plastic bag.
• Use sticky tape to pick up any remaining fine particles.
• Wipe the area with a wet wipe. Also do the same on your shoes in case they have come into direct contact with the mercury powder.
• Place all cleanup materials in a sealable plastic bag
• Do not Vacuum as this can spread mercury all over the room.
• After cleanup place all the debris and cleanup materials in your trash container, outdoor. Or take them directly to the trash containers of your local waste management authorities.
• Wash your hands.
• Continue ventilating the room for several hours.

However, the amount of mercury in fluorescent lamps is very small. Therefore don't be so much worried these precautions are to help cleanup broken fluorescent lamps in the right way.

How do Transformers work?

A Transformer is a stationed device used for transforming electrical energy from one a.c circuit to another. It changes voltages from low to high or high to low without changing the frequency. A Transformer changing voltage from low to high voltage is called a Step-up Transformer whereas the one changing voltage from high to low voltage is called a Step-down Transformer.

figure 1. Step down Transformer

In order for a transformer to do its work it must follow a certain working principle and this is Faraday's law of electromagnetic induction. It states that the magnitude of the induced Electromotive force in a circuit is directly proportional to the rate of change of magnetic flux linked with the circuit.

The construction of a Transformer

A Transformer is made up of an iron core on which wires are wound to form Primary coil (P) and Secondary coil (S) as shown in figure 1 above. The primary coil is connected to the source of a.c supply and the secondary coil is connected to the load.
The iron core constitutes a number of laminations of soft iron but sometimes silicon steel is used instead to reduce Hysteresis loss.

figure 2. Transformer laminations

The laminations are insulated from each other with paper or vanish in order to minimize the eddy currents.

A current carrying conductor produces a magnetic field around it, and when this conductor is placed near a ferromagnetic material (like the transformer core) it induces a magnetic flux within the material. You might be asking yourself, 'why are ferromagnets chosen to be the core?' I think it's because they pose low reluctance to the flow of magnetic flux.

figure 3. Current carrying conductor

When the primary coil draws alternating current from its source, an alternating magnetic flux is induced in the iron core, see figure 1 above.

Whenever current changes direction, in the primary coil, the induced magnetic flux also changes direction (alternates) and whenever this happens the secondary coil cuts the magnetic flux and produces the voltage different from the supplied voltage.
Since the magnetic flux is alternating, the current which the secondary coil produces also alternates. This is mutual induction.

A transformer is housed in a metallic box to protect it from dust and sometimes the box is designed with fins on it for cooling purpose.

Distribution transformer

Transformers are used; in transmission system to step up voltage from 6.6 KV to 33 KV or 132 KV, in distribution system to step down voltage from 11 KV or 6.6 KV to 440 volts or 240 volts and in electronics.Transformers enable the transmission of electricity at high voltage with low current.

In electronics transformers step down voltage from 240 volts to other lower voltages.The picture below shows a switched mode power supply transformer.

Types of Transformers
There are two types of transformers namely:
1. Auto Transformer
2. Double wound Transformer

An Auto Transformer has its winding common to both Primary and Secondary circuit.

Auto transformer are usually used for starting induction motors and discharge lamps. But the one in the picture is used to step down voltage for a radio receiver.














The double wound transformer is the one I have been explaining earlier in this post.

What are Diodes?

A Diode is a semiconductor which can be used to change Electric Supply from Alternating Current to Direct Current. They allow current to pass through them in one direction.

Schematic Symbol

Rectifier diodes in a circuit

A Diode has two parts; the P-type semiconductor and the N-type semiconductor. The P-type semiconductor has holes (Positive charges) as the majority charge carriers and N-type has electrons (Negative charges) as the majority charge carriers.

Silicon or Germanium are the materials used to manufacture diodes. During manufacture, some impurity atoms are added to silicon. This is called doping. To produce the P-type semiconductor silicon is doped with Boron, for example, which introduces holes as majority charge carriers. Phosphorus can be added to silicon to produce N-type semiconductor. Phosphorus atoms offer their electrons to silicon in a covalent bond. There are also minority charge carriers in both semiconductors; the P-type has electrons as minority charge carriers and the N-type has holes as minority charge carriers.

P-type doping

N-type doping

Diode Bias

Diode bias is the condition of a diode.

No Bias

The No Bias condition, this is when there's no voltage applied. The layers of ions in the depletion region of the diode repel majority charge carriers, holes and electrons, of the P-type and N-type semiconductors and prevent them from crossing the junction.

Forward Bias (VD )
In the Forward Bias condition, also known as 'on' condition of the diode, a positive potential is applied to the P-type semiconductor and a negative potential is applied to N-type semiconductor. The ions in the depletion region get neutralized and eventually they will allow heavy flow of electrons. This is due to the pressurizing of electrons in the N-type semiconductor.


The forward bias voltage of a germanium diode is 0.3 volts and that of a silicon diode is 0.6 volts. It is important to note the maximum forward current which can be allowed to pass through the diode. If too large current is allowed to pass through a diode, it can  easily get damaged.

Reverse Bias
In the reverse bias, the depletion region enlarges. When a positive potential is applied to the N-type semiconductor and the negative potential to the P-type semiconductor, the uncovered positive and negative ions in the depletion region increases. This is because the negative terminal of the voltage supply repels electrons in the P-type semiconductor and the positive terminal attracts electrons in the N-type semiconductor. Therefore conduction is not possible.