1. Discuss and explain the properties of electric charges
2. Identify five scientists and their contributions in the study of electric charges.
3. cite or quote three differences between charging by conduction and Induction, give 2 examples for each type.
1. The properties of electric charges are:
a) Charge: Electric charge is a fundamental property of matter. It can be either positive or negative. Like charges repel each other, while opposite charges attract each other.
b) Conservation of charge: Electric charge is conserved, which means it cannot be created or destroyed. In any closed system, the total charge remains constant.
c) Quantization of charge: Electric charge exists in discrete units called elementary charges. The smallest unit of charge is the charge of an electron (-1.6 x 10^-19 coulombs).
d) Coulomb's law: It describes the force between two charged objects. According to this law, the force is directly proportional to the product of their charges and inversely proportional to the square of the distance between them.
e) Electric fields: An electric charge creates an electric field in its surroundings. Other charges placed in this electric field experience a force due to the interaction of the fields.
2. Five scientists and their contributions in the study of electric charges are:
a) Benjamin Franklin: He conducted experiments with electricity and discovered the concept of positive and negative charges. He also proposed the theory of electric fluid and the concept of an electric circuit.
b) Charles-Augustin de Coulomb: He formulated Coulomb's law, which describes the mathematical relationship between the force, charges, and distance in an electrostatic system.
c) Michael Faraday: He discovered the concept of electric and magnetic fields and their relationship through his experiments with electromagnetism. He also introduced the concept of electric and magnetic field lines.
d) Alessandro Volta: He invented the first battery, known as the Voltaic pile, which acted as a continuous source of electric charges.
e) Thomas Edison: He made significant contributions to the study of electric charges through his inventions and improvements in electrical systems. He developed practical applications for electricity, including the electric light bulb and the electric power distribution system.
3. Differences between charging by conduction and induction:
Charging by conduction:
- Definition: Charging by conduction occurs when a charged object is brought into direct contact with a neutral object, causing the neutral object to acquire the same charge as the charged object.
- Examples: Rubbing a balloon on hair and transferring the charge to the balloon, or touching a positively charged rod to a neutral conductor and allowing the charge to spread throughout the conductor.
Charging by induction:
- Definition: Charging by induction occurs when a charged object is brought near a neutral object, causing the separation of charges in the neutral object, without direct contact with the charged object.
- Examples: Bringing a negatively charged object near a neutral conductor, causing the charges in the conductor to redistribute, or using a charged comb to attract neutral pieces of paper without touching them.
Two key differences between charging by conduction and induction are:
i) Direct contact: Charging by conduction requires direct contact between the charged object and the neutral object, while charging by induction does not require direct contact.
ii) Redistribution of charges: In charging by conduction, the charges are transferred from the charged object to the neutral object, leading to the neutral object acquiring the same charge. In charging by induction, the charges in the neutral object are redistributed, resulting in separation of charges but not necessarily acquiring the same charge as the charged object.