Physics Flashcards
What is electric current defined as?
The rate of flow of electric charge through any section of a conductor
Electric current is measured in amperes.
What is the SI unit of electric charge?
Coulomb (C)
The SI unit is used to quantify electric charge.
What does Coulomb’s Law state?
The force of attraction or repulsion between two point charges is directly proportional to the product of the charges and inversely proportional to the square of the distance between them
Mathematically, F = K * (q1 * q2) / r², where K is a constant.
What is the law of conservation of charge?
Electric charges can neither be created nor destroyed; they can only be transferred from one body to another
This principle is fundamental in electrostatics.
What are the two types of electric charge in nature?
- Positive charge
- Negative charge
These charges exhibit attractive and repulsive forces.
What is the conventional direction of current?
The direction of motion of positive charges through the conductor
This is opposite to the direction of negatively charged electrons.
What is an electric circuit?
The closed path along which an electric current flows
An electric circuit must be complete for current to flow.
What is the SI unit of electric current?
Ampere
One ampere is defined as one coulomb of charge flowing through a conductor in one second.
True or False: Electric current is a scalar quantity.
True
Unlike vector quantities, it does not have a direction associated with it.
Fill in the blank: The electric field around a charged body is the region within which its _______ can be experienced.
influence
The electric field describes the effect of the charge in the surrounding space.
What does static electricity deal with?
Electric charges at rest
In contrast, current electricity deals with charges in motion.
What is the relationship between resistance in series and parallel combinations?
- Series: Total resistance increases
- Parallel: Total resistance decreases
The configuration affects how resistors behave in a circuit.
What is the fundamental law of electrostatics?
Like charges repel and unlike charges attract each other
This law explains the behavior of charged objects.
What factors affect the resistance of a conductor?
- Material of the conductor
- Length of the conductor
- Cross-sectional area
Temperature can also affect resistance.
What is the relationship between voltage (V), current (I), and resistance (R)?
V = I * R
This is known as Ohm’s Law.
What is the heating effect of electric current?
The phenomenon where electric current generates heat in a conductor
This effect is utilized in devices like toasters and electric heaters.
What is electrostatic potential?
The amount of work done in bringing a unit positive charge from infinity to a point in an electric field.
Its unit is volt.
What is the unit of electrostatic potential?
Volt
What is the formula for potential difference between two points?
Potential difference = Work done / Charge
What is one volt defined as?
One joule of work done in bringing a positive charge of one coulomb from one point to another.
What is an electrochemical or voltaic cell?
A device which converts chemical energy into electrical energy.
What is the purpose of a galvanometer?
To detect current in an electric circuit.
What is an ammeter?
A device to measure current in a circuit, functioning as a low resistance galvanometer.
What is the purpose of a voltmeter?
To measure the potential difference across components in a circuit.
What does Ohm’s law state?
The current passing through a conductor is directly proportional to the potential difference across its ends.
What is resistance in terms of electric circuits?
The property of a conductor that opposes the flow of current.
What factors affect the resistance of a conductor?
The nature of the material, length of the conductor, and cross-sectional area.
Resistance is given by the formula: R = ρ(L/A), where ρ is resistivity.
What happens to the resistivity of metallic conductors with temperature?
It increases with the increase of temperature.
What are resistances in series?
When two or more resistances are joined end to end, so that the same current flows through each one.
What is the formula for total resistance in series?
R_total = R1 + R2 + R3 + …
What are resistances in parallel?
When two or more resistances are connected across two points, providing separate paths for current.
What is the formula for total resistance in parallel?
1/R_total = 1/R1 + 1/R2 + 1/R3 + …
What is the heating effect of current?
Heat produced in a conductor when an electric current passes through it.
What does Joule’s law of heating state?
The heat produced is directly proportional to the square of the current, resistance, and time.
What is electric energy?
The total work done in maintaining an electric current in a circuit for a given time.
What is the unit of power in electrical terms?
Watt
Fill in the blank: The electric heating effect is utilized in appliances such as _______.
electric iron, room heaters, water heaters, electric bulbs.
What is electrical power?
The rate at which electric energy is consumed by an appliance.
What is the formula for electrical power?
P = VI = I²R = W/t
What is the SI unit of power?
Watt (W)
What defines 1 watt?
The power of an appliance is 1 watt if one ampere of current flows through it on applying a potential difference of 1 volt.
How is 1 joule defined in terms of volts and amperes?
1 joule = 1 volt × 1 ampere × 1 second
What is the relationship between watts and joules?
1 W = 1 J/s = 1 VA
How many watts are in a kilowatt?
1 kilowatt = 1000 W.
What is a kilowatt hour (kWh)?
The electrical energy consumed by an appliance of 1000 watts when used for one hour.
What does the power rating of an appliance indicate?
The electric energy consumed per second by the appliance when connected across the marked voltage of the mains.
What is the efficiency of an electrical device?
The ratio of the output power to the input power.
Fill in the blank: Efficiency, η = _______.
Output power / Input power
True or False: A kilowatt hour is equivalent to 3.6 x 10^6 joules.
True
What is Frictional Electricity?
Electricity produced by rubbing two suitable bodies and flow of electrons from one body to another
It occurs when materials like glass and silk are rubbed together, causing charge transfer.
Define Electricity.
A fundamental form of energy observable in positive and negative forms, expressed in terms of the movement and interaction of electrons
It can occur naturally (e.g., lightning) or be produced (e.g., generators).
What charge does a glass rod acquire when rubbed with silk?
Positive charge
This charge is due to the loss of electrons from the glass rod.
What charge does an ebonite rod acquire when rubbed with wool?
Negative charge
This is because the ebonite rod gains electrons from the wool.
What is Charge Conservation?
Charges are not created or destroyed but can be transferred or remain conserved
Example: When a glass rod is rubbed with silk, negative charges shift to the silk.
What is the SI unit of charge?
Coulomb
One coulomb repels an equal charge with a force of 9 x 10^9 N at a distance of 1 meter in vacuum.
What is the charge on an electron?
1.6 x 10^-19 coulomb
This is a fundamental constant in physics.
Define a Conductor.
A substance that allows the passage of electric charges easily, offering very low resistance
Examples include Copper, Silver, and Aluminium.
What is an Insulator?
A substance with infinitely high resistance that does not allow electric current to flow through it
Insulators are used to prevent unwanted current flow.
Define Electric Potential Energy.
The work required to bring charges to their respective locations against the electric field
This work is stored as potential energy of the charge.
What is the SI unit of resistance?
Ohm
One ohm allows a current of one ampere to flow with a potential difference of 1 volt.
What is Resistivity?
The resistance offered by a cube of material of side 1m when current flows perpendicular to its opposite faces
Its SI unit is ohm-metre (Ω·m).
What is a Resistor?
A conductor that has some appreciable resistance
Resistors are used to control current flow in circuits.
What is a Rheostat?
A device that changes the magnitude of current in a circuit by changing the resistance
It is connected in series and can act as a potential divider.
Define Semiconductors.
Materials having resistivity between that of insulators and conductors
They are commonly used in making integrated circuits.
