Electric Charge
An electric charge is a fundamental property of matter that describes the amount of electrical energy associated with an object. It is a fundamental property of particles such as protons, electrons, and ions, which are the building blocks of matter.
Electric charge is either positive or negative. Protons carry a positive charge, electrons carry a negative charge, and neutrons have no charge. Objects become charged when there is an imbalance of protons and electrons.
Like charges (positive-positive or negative-negative) repel each other, while opposite charges (positive-negative) attract each other. The unit of electric charge is the coulomb (C), and the amount of charge on an object is measured in coulombs.
Properties of Electric Charge
Here are some properties of electric charge:
- Charge is a fundamental property of matter: Charge is an intrinsic property of subatomic particles such as electrons and protons. It is an essential characteristic of matter that plays a fundamental role in electromagnetism.
- Charge is conserved: Electric charge cannot be created or destroyed. The total amount of charge in a closed system is constant, meaning that charges can only be transferred from one object to another.
- Charge is quantized: Electric charge comes in discrete units, called elementary charges. The elementary charge is the charge of a single electron or proton.
- Charge can be positive or negative: Electric charge can be positive or negative. Protons carry a positive charge, while electrons carry a negative charge.
- Like charges repel, opposite charges attract: Like charges repel each other, while opposite charges attract. This is why positive and negative charges are often referred to as “opposite” charges.
- Charge can be transferred by contact or induction: Electric charge can be transferred from one object to another by contact or induction. Contact occurs when two objects touch, while induction occurs when a charged object creates an electric field that induces a charge on another object without touching it.
- Charge is a source of electric fields: Charged particles create electric fields around them, which can exert forces on other charged particles in their vicinity.
- Charge can flow through conductors: Electric charge can flow through conductive materials, such as metals, due to the movement of electrons. This is the basis for electric current and electrical power.
Numerical Problems Based on Electric Charge for Class 12 Physics
Here we are providing numerical problems based on electric charge for class 12 physics. problems related to electric charge, types of charges and properties of charge are covered in this article.
Q.1. From a neutral body 106 electrons are removed. Calculate the charge on the body.
Ans. 1.6 × 10-13 coulomb.
Q.2. Calculate the charge on a body if one million electrons are removed from it. (one million = 10 lakh)
Ans. + 1.6 × 10-13 coulomb.
Q.3. Calculate the charge on a body if 105 electrons are added to it.
Ans. – 1.6 × 10-14 coulomb: Since electrons have been added, hence the body is – vely charged.
Q.4. Calculate the charge on a body if two billion electros are added to it.
Ans. – 3.2 × 10-10 coulomb.
Q.5. Calculate how many electrons may be removed from a body so that it may have a charge of + 1 coulomb.
Ans. 6.25 × 1018
Q.6. How many electrons may be removed from a body so that it may have a charge of (a) + 1 milli coulomb (b) + 1 micro coulomb.
Ans. (a) 6.25 × 1015 electrons, (b) 6.25 × 1012 electrons.
Q.7. How many electrons should be added to a body so that it may have a charge of (a) – 2 coulomb (b) – 5 milli coulomb (c) – 0 4 mC.
Ans. (a) 12.5 × 1018, (b) 31.25 × 1015; (c) 2.5 × 1012.
Q.8. Can a body have a charge of 4.8 × 10-18 coulomb?
Ans. Yes.
Q.9. Can a body have a charge of 4.8 × 10-20 coulomb?
Ans. No.
Q.10. Can a body have a charge (a) 0.32 × 10-18coulomb (b) 0.64 × 10-20 coulomb (c) 4.8 × 10-21 coulomb.
Ans. (a) Yes; (b) No; (c) No.
Q.11. Calculate the charge of an iron particle of mass 224 mg, if 001% of the electrons are removed from it.
Ans. 99.84 × 10-2 coulomb.
Q.12. Calculate the charge of a copper particle of mass 300 mg, if 0.1 % of the electrons are removed from it.
Ans. 1299.2 × 10-2 coulomb.
