Welcome to the world of physics, where the wonders of electricity come alive! In this set of 10th-grade physics notes, we delve into the captivating realm of Unit 14: Current Electricity. Unraveling the secrets of charge flow and electrical circuits, this unit serves as a gateway to understanding the fundamental principles that power our modern world. From Ohm’s Law to circuits and resistors, these comprehensive notes will illuminate the path to a deeper comprehension of the electrifying phenomena that surround us daily. So, let’s embark on this electrifying journey to empower our minds with knowledge and spark a fascination for the captivating world of current electricity.
10th Physics Unit 14 Long Question Notes
10th Physics Unit 14 MCQ’s Long Question Notes
10th Physics Unit 14 Numerical Notes
- 10th Class Pak Study Textbook
- 9th and 10th Class General Science Textbook
- Chapter No. 9 Notes 10th Chemistry
- Biology 10th Class Past Papers
- English Past Papers of 10th Class
10th Physics Unit 14 Short Question Notes
What constitutes electric current?
Answer: Charges in motion constitute electric current.
How is electric current produced in metals?
Answer: In metals, electric current is produced due to the flow of free electrons, i.e., negative charges.
In what materials is the current produced due to both positive and negative charges?
Answer: In solutions (electrolytes), the current is produced due to the flow of both positive and negative charges.
What is the SI unit of current?
Answer: The SI unit of current is ampere (A).
Define conventional current.
Answer: Conventional current is the current flowing from the positive terminal to the negative terminal of a battery due to the flow of positive charges.
How can we measure electric current in a circuit?
Answer: Electric current can be measured using instruments like a galvanometer or an ammeter.
How is a galvanometer different from an ammeter?
Answer: A galvanometer is a sensitive instrument that can detect small currents, while an ammeter is used to measure larger currents and is based on a modified galvanometer.
What is the relationship between charge (Q) and current (I)?
Answer: The relationship between charge (Q) and current (I) is given by I = Q/t, where ‘t’ is the time taken for the charge to pass through the circuit.
What is the conventional current direction in a circuit connected to a battery?
Answer: The conventional current flows from the positive terminal to the negative terminal of the battery.
How can a battery produce current in a circuit?
Answer: A battery produces current by separating positive and negative electric charges within it, creating a potential difference between its terminals, which drives the flow of charges through a connected circuit.
What causes a potential difference between two ends of a conductor?
Answer: Connecting one end of the conductor to the positive terminal and the other end to the negative terminal of a battery causes a potential difference between the two ends.
What is the role of a battery in the flow of current through a conductor?
Answer: The battery provides the potential difference necessary for the steady flow of current in the conductor.
What happens to electrical energy as charges flow through a circuit?
Answer: Electrical energy is converted into other forms, such as heat and light, as charges flow through the circuit.
What is the SI unit of potential difference?
Answer: The SI unit of potential difference is the volt (V).
Define electromotive force (e.m.f).
Answer: Electromotive force (e.m.f) is the energy supplied by a battery to a unit positive charge when it flows through a closed circuit, or the energy converted from non-electrical forms to electrical form when one coulomb of positive charge passes through the battery.
How is potential difference across a circuit component measured?
Answer: The potential difference across a circuit component can be measured using a voltmeter connected directly across the terminals of the component.
Where should a voltmeter be connected to measure potential difference?
Answer: A voltmeter should be connected in parallel with the component across which the potential difference is to be measured.
How is the electromotive force (e.m.f.) of a battery measured?
Answer: The e.m.f. of a battery is measured by connecting a voltmeter directly to the terminals of the battery when it is not driving current in the external circuit.
What is Ohm’s law?
Answer: Ohm’s law states that the current passing through a conductor is directly proportional to the potential difference applied across its ends, provided the temperature and physical state of the conductor do not change. It can be represented as V = IR, where V is the potential difference, I is the current, and R is the resistance.
What is the SI unit of resistance?
Answer: The SI unit of resistance is ohm, denoted by the symbol Ω.
What is the relationship between resistance and length of a wire?
Answer: The resistance of a wire is directly proportional to its length. R ∝ L.
How does the resistance of a wire depend on its cross-sectional area?
Answer: The resistance of a wire is inversely proportional to its cross-sectional area. R ∝ 1/A.
What is specific resistance?
Answer: Specific resistance, represented by the symbol ρ (rho), is a constant of proportionality that depends on the nature of the conductor material. It relates resistance, length, and cross-sectional area of a wire and is measured in ohm-meters (Ω m).
Why are metals like copper and silver good conductors of electricity?
Answer: Metals like copper and silver have excess free electrons that are not strongly bound to any particular atom. These free electrons can move easily in response to an external electric field, allowing metals to conduct electricity with ease.
What happens to the resistance of a conductor with an increase in temperature?
Answer: The resistance of a conductor increases with an increase in temperature. This is because the higher temperature leads to more collisions between electrons and atoms in the conductor, impeding the flow of current.
What are insulators?
Answer: Insulators are materials that do not allow electric charges (specifically, electrons) to move freely through them.
Why can’t electric current flow through insulators?
Answer: Insulators have electrons tightly bound within their atoms, so there are no free electrons available to carry electric current.
Give examples of insulators.
Answer: Examples of insulators include rubber, glass, wood, plastic, fur, and silk.
Why does diamond not conduct electricity?
Answer: Diamond does not conduct electricity because it has no free electrons available for conducting electric current.
Why is diamond a good conductor of heat?
Answer: Diamond is a good conductor of heat because its particles are very firmly bonded together, allowing heat to be transferred efficiently.
How can jewellers differentiate between a real diamond and a fake one made from glass?
Answer: Jewellers can tell if a diamond is real or fake by holding it to their lips. A real diamond feels very cold due to its excellent ability to transfer heat, which is about four to five times better than copper.
What is the main difference between series and parallel combinations of resistors?
Answer: In series combination, resistors are connected end-to-end, and the current passing through each resistor is the same. In parallel combination, one end of each resistor is connected to the positive terminal of the battery, and the voltage across each resistor is the same.
How is the equivalent resistance calculated for resistors in series?
Answer: The equivalent resistance for resistors in series is the sum of their individual resistances.
How is the equivalent resistance calculated for resistors in parallel?
Answer: The reciprocal of the equivalent resistance for resistors in parallel is equal to the sum of the reciprocals of their individual resistances.
What are some examples of insulators commonly used in daily life?
Answer: Some common examples of insulators used in daily life include rubber gloves, plastic water bottles, glass windows, and wooden furniture.
What is the process that continuously moves charges from a higher electric potential to a lower potential, becoming a continuous source of electrical energy?
Answer: The process is when charge moves from a higher electric potential to a lower potential, delivering electric current.
What is Joule’s law, and how is it stated?
Answer: Joule’s law states that the amount of heat generated in a resistance due to the flow of charges is equal to the product of the square of the current (I), resistance (R), and the time duration (t). Mathematically, it is expressed as W = I^2Rt.
How is electrical power defined and calculated?
Answer: Electrical power (P) is the amount of energy supplied by current in unit time. It can be calculated using the formula P = VI, where V is the voltage and I is the current.
What type of current does a battery provide – direct current (d.c.) or alternating current (a.c.)?
Answer: A battery provides direct current (d.c.).
Define Joule’s law and state its equation.
Answer: Joule’s law states that the amount of heat generated in a resistance due to the flow of charges is equal to the product of the square of current (I), resistance (R), and the time duration (t). The equation for Joule’s law is: W = I^2Rt.
What is the unit of electric power?
Answer: The unit of electric power is the watt (W), which is equal to one joule per second (1 Js^-1).
How is the energy supplied by a current in unit time known?
Answer: The energy supplied by a current in unit time is known as electric power.
What is the time period of alternating current (a.c.) in Pakistan?
Answer: The time period of alternating current in Pakistan is 1/50th of a second, as the frequency is 50 Hz.
What are the three wires used in house wiring, and what are their purposes?
Answer: The three wires used in house wiring are:
Livewire (L): It carries the high potential and delivers electrical energy to the appliances.
Neutral wire (N): It provides the return path for the current and is maintained at zero potential.
Earthwire (E): It carries no electricity and is connected to the ground to protect against electrical faults.
How are electrical appliances connected in a household electric circuit?
Answer: Electrical appliances are connected in parallel to the power source in a household electric circuit. This means they all get the full mains voltage, and one can turn ON any appliance without affecting others.
What are the major hazards of electricity?
Answer: The major hazards of electricity are electric shock and fire. Electric shock can occur when someone comes into contact with live wires or appliances. Fire can result from faulty wiring or electrical equipment.
What is the voltage and current level that can be fatal to humans?
Answer: Voltage above 50 volts and current above 50 milliamperes (mA) can be fatal to humans.
How can a person be protected from electric shock while using electrical appliances?
Answer: To protect from electric shock while using electrical appliances, it is essential to ensure proper grounding of electrical devices, use circuit breakers and fuses, avoid touching live wires, and follow electrical safety guidelines.
Why are electrical wires insulated?
Answer: Electrical wires are insulated with a plastic cover for safety purposes.
What can cause damage to the insulation of electrical wires?
Answer: Exceeding the rated current carrying capacity of the conductor, leading to overheating, can damage the insulation of electrical wires.
What is a short circuit?
Answer: A short circuit occurs when a circuit with very low resistance is formed, causing a large current to flow.
How can short circuits be caused in electrical circuits with parallel appliances?
Answer: Connecting additional appliances in parallel reduces the equivalent resistance, increasing the current through the wires, which can cause enough thermal energy to melt the insulation and cause a short circuit or fire.
What is the purpose of a fuse in an electric circuit?
Answer: A fuse is a safety device connected in series with the live wire to protect the equipment when excess current flows. It melts when a large current passes through it, breaking the circuit.
How does a circuit breaker work?
Answer: A circuit breaker disconnects the supply automatically if the current exceeds the normal value. It uses an electromagnet to separate the contacts when a fault occurs, and the contacts can be pushed back together after the fault is repaired.
What is the purpose of an earthwire in household electrical circuits?
Answer: The earthwire provides a safe route for current to flow through if the livewire touches the metal casing of an appliance, preventing electric shock to the user.
How can you avoid insulation damage in electrical wires?
Answer: Insulated wires should not be exposed to constant friction or excessive moisture. Using cables with two layers of insulation can help prevent damage in such situations.
What precautionary measures should be taken while using fuses in household electrical circuits?
Answer: Fuses should have slightly more rating than the current drawn by the electrical appliance under normal conditions. They should be connected in the live wire, and the main power should be switched off before changing any fuse.