23.0.0: ELECTRIC CHARGES:
PRODUCTION OF ELECTRIC CHARGE:
Electric charge is produced when a substance either gain or loses electron when two substances are robbed together. One substance gains electron while the other substance loses electron.
TYPES OF CHARGES:
There are two types of electric charges:
Positive charge
Negative charge
FORMATION OF POSITIVE CHARGE:
A positive charge is formed when a substance loses electron to another substance. A positive charge is formed when a glass rod is robbed with silk. The glass become positively charged while the silk become negatively charged.
FORMATION OF NEGATIVE CHARGE:
A negative charge is formed when a gains electron from another substance. A negative charge is formed when ebonite rode is robbed with fur. The fur become positively charged while the ebonite become negatively charged.
STATIC ELECTRICITY:
Every substances is made of atom which has a nucleus. The nucleus contains proton and neutron. The electron reside in the shell. Every atom is neutral because it contain the same number of electrons as protons. When an atom of one substance is robbed with that of another substance, the atom of one substance will gain electron and become negatively charged because it now has more electron than protons while the atom of the other substance will loose electron and becomes positively charged because it now has less electrons than protons..
LAWS OF ELECTROSTATIC:
The law of electrostatic states that like charges repel each other while unlike charges attract each other.
GOLD LEAF ELECTROSCOPE:
Gold leaf electroscope is an instrument that has a gold leaf, that is used to detect and test small electric charge.
DJAGRAM OF GOLD LEAF ELECTROSCOPE:
EXPLANATION OF GOLD LEAF ELECTROSCOPE:
Gold leaf electroscope consist of a flat brass plate and a brass rod with a gold leaf attached at the end of the rod. The brass rod is insulated from the metal case and is housed to protect the gold leaf from draught. The case is earthed.
HOW TO CHARGE THE GOLD LEAF ELECTROSCOPE:
The gold leaf electroscope can be charged by the following:
Charging By contact methods:
By contact method, the gold leaf is charged by sliding a charged body on the brass cap. The charge lasses from the charged body down to the gold leaf. Then the gold leaf deflect to show that it is charged.
Charging by electrostatic induction method:
A charged body is brought near the cap of the electroscope without touching it. The gold leaf would be charged and the leaf will reflects to show that it is charged.
HOW TO USE GOLD LEAF TO DETECT AND MEASURE ELECTRIC CHARGE:
First of all, discharge the gold leaf electroscope. Use a known charge say positive charge and charge the gold leaf electroscope. The gold leaf will deflect showing that it is charged. Place an unknown charge unto the brass cap. If the gold leaf deflect further, it means that the unknown charge is a positive charge. But if the gold leaf collapse, it means that the unknown charge is a negative charge. The extent by which the gold leaf deflect further or collapse indicate the size of the electric charge.
DISTRIBUTION OF CHARGES ON CONDUCTORS:
Charges are concentrated at the sharp pointed end of a conductor.
DIAGRAM TO SHOW CHARGE DISTRIBUTION:
CHARGE DENSITY:
Charge density of a conductor is the charge per unit area of the conductor. Charge density is highest at the sharpest point of the conductor because the sharpest point of the conductor has the smallest surface area where the concentration of charges is high.
ACTION AT A POINT OR POINT ACTION:
charges are concentrated at the sharp point of a conductor.
Action at a point is the process whereby when a sharp pointed conductor is placed in air, the concentration of the charges at the sharp point of the conductor causes air molecules near the conductor to be ionized. I.e the positive and negative ions in the atom of the air molecule are separated. If the sharp pointed conductor is positively charged, it will attract the negative ions towards itself and repelled the positive ions. The repelled positive ions will collide with more air molecules and cause more ionization of air molecules.. This process keep on repeating itself and therefore form a charged cloud wind or electric wind.
LIGHTNING:
Lightning is a bright flash that is formed due to electrical discharge. It occurs when electrical charges that are formed in thundercloud build up such that the attraction between unlike charges within a cloud or between clouds steadily increase until opposite charges suddenly jump from one cloud to another. The sound of the spark is the thunder we d hear while the flash is the lightning. Great amount of heat is produced and can set a building on fire.
LIGHTNING CONDUCTOR:
A lightning conductor is used to provide a safety path for electrical discharge and to protect a building from being damaged by lightning.
DESCRIPTION OF LIGHTNING CONDUCTOR:
Lightning conductor consists of a sharp pointed conductor or metal rod that is attached to the highest point of a building. The conductor is connected by a thick copper cable to a copper plate buried in the ground beside the building.
WORKING PRINCIPLE OF LIGHTNING CONDUCTOR:
Lightning conductor works on the principles of action at a point. This is explained above. The large copper cable is capable to carry the the large current released during lightning to the ground without melting due to overheating. Large copper cable is used so that the resistance of the circuit is very low to prevent overheating when excess current is flowing through the copper cable.
DIAGRAM SHOWING LIGHTNING CONDUCTOR:
ELECTROPHORUS:
Electrophorus is a device that is used for transferring and storing electric charges. Electrophorus produces charges by electrostatic induction
METHODS OF CHARGING A NEUTRAL BODY
There are three methods of charging a neutral body. The methods are :
Contact method
Friction method
Induction method
CONTACT METHOD OF CHARGING NEUTRAL BODY:
In contact method of charging a neutral body, the neutral body is placed in contact with a known charged object. In a neutral body, the positive and negative charges are arranged in such a way that they cancel one another. When a charge object, say positively charged object is placed in contact with a neutral object, the positive charges in the charged object attract the negative charges in the neutral object toward its side and repel the positive charges to the other side of the neutral object. After some times, the positive charges are arranged at one side of the neutral object while the negative charges are arranged at the other side of the neutral object. The object is then earthed or touched with the tip of the finger so that the negative charges are conducted to the ground. After that, the object becomes positively charged.
DIAGRAM:
FRICTION METHOD OF CHARGING A NEUTRAL BODY:
In friction method, a charged object ( say positive charge) is used to rob with a neutral object. the positive charges in the charged object attract the negative charges in the neutral object toward its side and repel the positive charges to the other side of the neutral object. After some times, the positive charges are arranged at one side of the neutral object while the negative charges are arranged at the other side of the neutral object. The object is then earthed or touched with the tip of the finger so that the negative charges are conducted to the ground. After that, the object becomes positively charged.
DIAGRAM:
INDUCTION METHOD OF CHARGING A NEUTRAL BODY:
In induction method, a charged object ( say positive charged object ) is placed near a neutral object. the positive charges in the charged object attract the negative charges in the neutral object toward its side and repel the positive charges to the other side of the neutral object. After some times, the positive charges are arranged at one side of the neutral object while the negative charges are arranged at the other side of the neutral object. The object is then earthed or touched with the tip of the finger so that the negative charges are conducted to the ground. After that, the object becomes positively charged.
SETUP DIAGRAM:
the figure shows the stages that are involved in induction method of charging neutral object.
PRODUCTION OF ELECTRIC CHARGE:
Electric charge is produced when a substance either gain or loses electron when two substances are robbed together. One substance gains electron while the other substance loses electron.
TYPES OF CHARGES:
There are two types of electric charges:
Positive charge
Negative charge
FORMATION OF POSITIVE CHARGE:
A positive charge is formed when a substance loses electron to another substance. A positive charge is formed when a glass rod is robbed with silk. The glass become positively charged while the silk become negatively charged.
FORMATION OF NEGATIVE CHARGE:
A negative charge is formed when a gains electron from another substance. A negative charge is formed when ebonite rode is robbed with fur. The fur become positively charged while the ebonite become negatively charged.
STATIC ELECTRICITY:
Every substances is made of atom which has a nucleus. The nucleus contains proton and neutron. The electron reside in the shell. Every atom is neutral because it contain the same number of electrons as protons. When an atom of one substance is robbed with that of another substance, the atom of one substance will gain electron and become negatively charged because it now has more electron than protons while the atom of the other substance will loose electron and becomes positively charged because it now has less electrons than protons..
LAWS OF ELECTROSTATIC:
The law of electrostatic states that like charges repel each other while unlike charges attract each other.
GOLD LEAF ELECTROSCOPE:
Gold leaf electroscope is an instrument that has a gold leaf, that is used to detect and test small electric charge.
DJAGRAM OF GOLD LEAF ELECTROSCOPE:
EXPLANATION OF GOLD LEAF ELECTROSCOPE:
Gold leaf electroscope consist of a flat brass plate and a brass rod with a gold leaf attached at the end of the rod. The brass rod is insulated from the metal case and is housed to protect the gold leaf from draught. The case is earthed.
HOW TO CHARGE THE GOLD LEAF ELECTROSCOPE:
The gold leaf electroscope can be charged by the following:
Charging By contact methods:
By contact method, the gold leaf is charged by sliding a charged body on the brass cap. The charge lasses from the charged body down to the gold leaf. Then the gold leaf deflect to show that it is charged.
Charging by electrostatic induction method:
A charged body is brought near the cap of the electroscope without touching it. The gold leaf would be charged and the leaf will reflects to show that it is charged.
HOW TO USE GOLD LEAF TO DETECT AND MEASURE ELECTRIC CHARGE:
First of all, discharge the gold leaf electroscope. Use a known charge say positive charge and charge the gold leaf electroscope. The gold leaf will deflect showing that it is charged. Place an unknown charge unto the brass cap. If the gold leaf deflect further, it means that the unknown charge is a positive charge. But if the gold leaf collapse, it means that the unknown charge is a negative charge. The extent by which the gold leaf deflect further or collapse indicate the size of the electric charge.
DISTRIBUTION OF CHARGES ON CONDUCTORS:
Charges are concentrated at the sharp pointed end of a conductor.
DIAGRAM TO SHOW CHARGE DISTRIBUTION:
CHARGE DENSITY:
Charge density of a conductor is the charge per unit area of the conductor. Charge density is highest at the sharpest point of the conductor because the sharpest point of the conductor has the smallest surface area where the concentration of charges is high.
ACTION AT A POINT OR POINT ACTION:
charges are concentrated at the sharp point of a conductor.
Action at a point is the process whereby when a sharp pointed conductor is placed in air, the concentration of the charges at the sharp point of the conductor causes air molecules near the conductor to be ionized. I.e the positive and negative ions in the atom of the air molecule are separated. If the sharp pointed conductor is positively charged, it will attract the negative ions towards itself and repelled the positive ions. The repelled positive ions will collide with more air molecules and cause more ionization of air molecules.. This process keep on repeating itself and therefore form a charged cloud wind or electric wind.
LIGHTNING:
Lightning is a bright flash that is formed due to electrical discharge. It occurs when electrical charges that are formed in thundercloud build up such that the attraction between unlike charges within a cloud or between clouds steadily increase until opposite charges suddenly jump from one cloud to another. The sound of the spark is the thunder we d hear while the flash is the lightning. Great amount of heat is produced and can set a building on fire.
LIGHTNING CONDUCTOR:
A lightning conductor is used to provide a safety path for electrical discharge and to protect a building from being damaged by lightning.
DESCRIPTION OF LIGHTNING CONDUCTOR:
Lightning conductor consists of a sharp pointed conductor or metal rod that is attached to the highest point of a building. The conductor is connected by a thick copper cable to a copper plate buried in the ground beside the building.
WORKING PRINCIPLE OF LIGHTNING CONDUCTOR:
Lightning conductor works on the principles of action at a point. This is explained above. The large copper cable is capable to carry the the large current released during lightning to the ground without melting due to overheating. Large copper cable is used so that the resistance of the circuit is very low to prevent overheating when excess current is flowing through the copper cable.
DIAGRAM SHOWING LIGHTNING CONDUCTOR:
ELECTROPHORUS:
Electrophorus is a device that is used for transferring and storing electric charges. Electrophorus produces charges by electrostatic induction
METHODS OF CHARGING A NEUTRAL BODY
There are three methods of charging a neutral body. The methods are :
Contact method
Friction method
Induction method
CONTACT METHOD OF CHARGING NEUTRAL BODY:
In contact method of charging a neutral body, the neutral body is placed in contact with a known charged object. In a neutral body, the positive and negative charges are arranged in such a way that they cancel one another. When a charge object, say positively charged object is placed in contact with a neutral object, the positive charges in the charged object attract the negative charges in the neutral object toward its side and repel the positive charges to the other side of the neutral object. After some times, the positive charges are arranged at one side of the neutral object while the negative charges are arranged at the other side of the neutral object. The object is then earthed or touched with the tip of the finger so that the negative charges are conducted to the ground. After that, the object becomes positively charged.
DIAGRAM:
FRICTION METHOD OF CHARGING A NEUTRAL BODY:
In friction method, a charged object ( say positive charge) is used to rob with a neutral object. the positive charges in the charged object attract the negative charges in the neutral object toward its side and repel the positive charges to the other side of the neutral object. After some times, the positive charges are arranged at one side of the neutral object while the negative charges are arranged at the other side of the neutral object. The object is then earthed or touched with the tip of the finger so that the negative charges are conducted to the ground. After that, the object becomes positively charged.
DIAGRAM:
INDUCTION METHOD OF CHARGING A NEUTRAL BODY:
In induction method, a charged object ( say positive charged object ) is placed near a neutral object. the positive charges in the charged object attract the negative charges in the neutral object toward its side and repel the positive charges to the other side of the neutral object. After some times, the positive charges are arranged at one side of the neutral object while the negative charges are arranged at the other side of the neutral object. The object is then earthed or touched with the tip of the finger so that the negative charges are conducted to the ground. After that, the object becomes positively charged.
SETUP DIAGRAM:
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| Induction method of charging neutral object |