F5 Flashcards
resultant force
a single force that represents the vector sum of two or more forces acting on an object
resolution of forces
process of resolving a force into two components
equilibrium of forces
forces acting on an object produce a zero resulting force
elasticity
the property of an object to return to its original shape and size after the force applied on it is removed
hooke’s law
extension of a spring is directly proportional to the force applied on the spring provided the elastic limit of the spring has not been exceeded
frictional force
the force that oppose the motion of an object
Pressure
Force per unit area
Atmospheric pressure
Pressure due to the weight of the layer of air acting on the surface of the Earth
Gas pressure
The force per unit area exerted by gas molecules as they collide with the wall of the container
Pascal’s Principle
Pressure applied on an enclosed fluid is transmitted uniformly is all directions in the fluid
Hydraulic system
A system that uses liquid to transmit pressure
Buoyant force
Force acting upwards on an object immersed in a liquid when there is pressure difference between the upper surface and lower surface of the object
Archimedes’ Principle
An object which is partially or fully immersed in a fluid will experience a buoyant force that is equal to the weight of the fluid displaced
Bernoulli’s Principle
When the velocity of the fluid increases, the pressure in the fluid decreases and vice versa
Electric field
Region around a charged particle where any electric charge in the region will experience an electric force
Electric field strength
Electric force acting on a unit of positive charge placed at a point
Current
Rate of flow of charge
Potential difference
Work done in moving one coulomb of charge from one point to another
Ohm’s law
The potential difference is directly proportional to the current provided that the physical conditions are kept constant
Ohmic conductors
Conductors that obey Ohm’s Law
Resistance
Ratio of potential difference across the conductor to the electric current flowing through it
Resistivity of a conductor
A measure of a conductor’s ability to oppose the flow of electric current
Superconductors
Material that conducts electricity without any resistance
Critical temperature
The temperature when the resistivity of a superconductor becomes zero
Electromotive force
The energy transferred or work done by an electrical source to move one columb of charge in a complete circuit
200V, 4000W on an appliance
200J of energy is needed by an electrical source to move one coulomb of charge in a complete circuit
Internal resistance
The resistance caused by electrolyte in the dry cell
Electrical energy
The ability of the electric current to do work
Electric power
The rate of electrical energy transferred
Catapult field
Resultant magnetic field produced by the interaction between the magnetic field from a CCC and the magnetic field from a permanent magnet
Magnetic field
A region in the surrounding of a magnet which a magnetic material experiences a detectable force
Electromagnetic induction
Production of an induced e.m.f in a conductor when there is relative motion between the conductor and a magnetic field or when the conductor is in a changing magnetic field
Induced current
The current produced when there is a change in magnetic flux
Lenz’s law
Induced current always flows in the direction which opposes the change of magnetic flux that causes it
Faraday’s Law
The magnitude of induced emf is directly proportional to the rate of cutting of magnetic flux
Transformer
An electrical device which increases or creases an alternating voltage based on the principle of electromagnetic induction
Ideal transformer
Transformer that does not experience any loss of energy
Thermionic emission
The emission of free electrons from a heated metal surface
Cathode ray
Beams of electrons moving at high speeds in a vacuum
Semiconductor diode
Electric component which allows electric current to flow in one direction only
Rectification
The process of converting an alternating current into a direct current
Full-wave rectification
Process where both halves of every cycle of an alternating cycle is made to flow in the same direction
Transistor
An electric component which has 3 terminals
Radioactive decay
Process in which an unstable nucleus becomes more stable by emitting radioactive radiation
Alpha particle
Helium nucleus which consists of 2 protons and 2 neutrons
Beta particle
Fast-moving electron
Gamma ray
High-frequency electromagnetic waves
Half-life
The time taken for a sample of radioactive nuclei to decay to half of its initial number
Nuclear energy
Atomic energy released during reactions such as radioactive decay, nuclear fission and nuclear fusion
Nuclear fission
A nuclear reaction when a heavy nuclei splits into two or more lighter nuclei while releasing a large amount of energy
Nuclear fusion
Nuclear reaction in which small and light nuclei fuse to form a heavier nucleus while releasing large amount of energy
Chain reaction
A self-sustaining reaction in which the products of a reaction can initiate a similar reaction
Black body
An idealised body that is able to absorb all electromagnetic radiation that falls on it
Thermal radiation
Electromagnetic radiation that includes visible light and radiation that cannot be seen by the human eye such as infrared radiation
Quantum of energy
Discrete energy packet and not a continuous energy
Photoelectric effect
The emission of electrons from a metal surface when it is illuminated by a beam of light of a certain frequency
Work function
The minimum energy required for photoelectron to be emitted from a metal surface
Threshold frequency
The minimum frequency required to produce photoelectric effect on a metal
