General Flashcards
Define an electric circuit and list its essential components.
An electric circuit is a closed path through which an electric current flows. Essential components include a power source, conductors, load.
State Ohm’s Law and its mathematical equation
Ohm’s Law states that the voltage across a conductor is directly proportional to the current flowing through it, given constant temperature. Mathematically, V=IR, where V is voltage, I is current, and R is resistance.
Explain the difference between series and parallel circuits.
In a series circuit, components are connected in a single path, and the same current flows through each component. In a parallel circuit, components are connected across multiple paths, and the voltage across each component is the same.
What units are used to measure voltage, current, and resistance?
Voltage is measured in volts (V), current in amperes (A), and resistance in ohms (Ω).
How is power calculated in an electric circuit?
Power (P) is calculated using P=IV, where P is power in watts (W), I is current in amperes (A), and V is voltage in volts (V)
Name two safety measures used in electrical circuits and explain their functions.
Two safety measures are fuses and circuit breakers. Fuses break the circuit if the current exceeds a safe limit, while circuit breakers automatically switch off in case of overcurrent to prevent damage or hazards.
What is the difference between instantaneous and average velocity?
Average velocity is the total displacement of an object over a given time interval, divided by the total time taken. Instantaneous velocity, on the other hand, is the velocity of an object at a specific instant or moment in time.
How does an increase in voltage affect energy consumption in an electrical device?
An increase in voltage leads to an increase in power consumption in an electrical device, as power is directly proportional to voltage when resistance is constant ( P=VI ).
List and define the three primary states of matter.
The three primary states of matter are:
Solid: Definite shape and volume, particles tightly packed.
Liquid: Definite volume but takes the shape of its container, particles less tightly packed than solids.
Gas: Neither definite shape nor volume, fills the container completely, particles widely spaced.
Explain the processes involved in changing states of matter
Changes of state involve adding or removing energy (heat):
Melting: Solid to liquid (add heat).
Freezing: Liquid to solid (remove heat).
Vaporization: Liquid to gas (add heat).
Condensation: Gas to liquid (remove heat).
Sublimation: Solid to gas or vice versa without passing through the liquid state.
What is the difference between transverse and longitudinal waves?
Transverse Waves: Particles oscillate perpendicular to the direction of wave propagation (e.g., light waves).
Longitudinal Waves: Particles oscillate parallel to the direction of wave propagation (e.g., sound waves).
Explain the phenomena of diffraction in waves.
Diffraction: Bending of waves around obstacles or through openings.
Define the formula for calculating wave speed
v = fλ
List examples of electromagnetic waves and their uses.
Electromagnetic waves include radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays. They are used in communication, medicine, and various technologies.
List and describe the three primary types of radiation.
Alpha (α) Radiation: Consists of helium nuclei (2 protons, 2 neutrons), low penetration, stopped by paper or skin.
Beta (β) Radiation: High-speed electrons or positrons, moderate penetration, stopped by a few millimeters of aluminum.
Gamma (γ) Radiation: High-energy electromagnetic waves, high penetration, requires thick lead or concrete to attenuate.
Define radioactivity
Radioactivity is the spontaneous emission of particles or electromagnetic radiation from unstable atomic nucle
Define ionizing radiation and its impact on matter
Ionizing radiation possesses enough energy to remove electrons from atoms, creating ions. It can damage biological tissues and DNA, posing health risks
What is an ion?
An ion is an atom or molecule that has an unequal number of protons and electrons, resulting in a net electrical charge
What are Newton’s 3 laws of motion?
First Law (Law of Inertia): An object at rest remains at rest, and an object in motion remains in motion with constant velocity unless acted upon by an external force.
Second Law (F = ma): The force acting on an object is directly proportional to its mass and acceleration.
Third Law (Action-Reaction): For every action, there is an equal and opposite reaction.
Define force and its unit of measurement
Force is a push or pull acting on an object, measured in Newtons (N)
What is the difference between weight and mass?
Mass is the amount of matter in an object, measured in kilograms (kg). Weight is the force acting on an object due to gravity, measured in Newtons (N).
What happens to the power dissipated in a circuit when a resistance is added in parallel?
The power dissipated increases
Using the kinetic model of gases, explain what happens to the pressure of the air inside the pump as its volume decreases.
Individual particles collide with container/walls more frequently and so the force on the walls is greater & pressure increases
State what is meant by an activity of 80 kBq
80 000 nuclei decays per second
What is meant by the period of a wave?
The period of a wave is the time taken for one wave to pass.
What are the SI units for mass, time, length, electrical current and temperature?
Kilograms, Seconds, Metres, Amperes, Kelvin
What do the prefixes (n) and (G) mean?
n - nano = 0.000000001;
G - giga = 1000000000
Why would a hilly area receive radio signal but not TV?
Radio waves and TV waves belong to different frequency bands. Radio waves typically have longer wavelengths and can diffract around obstacles like hills more effectively than TV waves
What is the significance of the potential difference in a circuit?
The potential difference, or voltage, is a measure of the energy given to charge carriers in a circuit. It represents the work done on a charge as it moves between two points in the circuit.
What is meant by refraction of light?
Refraction of light is the phenomenon where light changes direction and speed as it passes from one transparent medium to another.
Name a source of background radiation
Cosmic rays, terrestrial radiation (radon gas), medical tests, nuclear fallout…
Explain in terms of electron flow what is meant by alternating current.
direction of electron flow continually changing back and forth
State what is meant by an activity of 80 kBq
80 000 (nuclei) decay(s) per unit time
What is the speed of microwave signals in air
300,000,000 m/s
Define the term “temperature”
A measure of the average kinetic energy in the particles of an object
Define the term “specific heat capacity”
The amount of heat energy required to change the temperature of 1kg of a substance by 1 degree C
What do all waves transfer?
Energy
What is 1 Hz equivalent to?
1 per second
