Definitions (ALL) Flashcards
Define physical quantity
A quantity that can be measured and consists of magnitude and unit
Define base quantities
A set of independent physical quantities
Define oscillation(pendulum)
The regular repeating, back-and-forth motion of a simple pendulum
Define period of oscillation
Time taken for one complete oscillation
Define incident ray
The light ray going towards the surface
Define reflected ray
The light ray going away from the surface
Define point of incidence
The point at which incident ray strikes the surface
Define normal
The perpendicular line to the surface at the point of incidence
Define angle of incidence
The angle between the incident ray and the normal
Define angle of reflection
The angle between the reflected ray and the normal
Define refraction
Refraction is the bending of light as it passes from one medium to another medium of different optical density
Define refracted ray
Light ray that enters a medium and undergoes a change of direction
Define refractive index
The ratio of speed of light in vacuum to speed of light in medium
Define total internal reflection
Complete reflection of a light ray in an optically denser medium at the boundary with an optically less dense medium
Define critical angle c
The angle of incidence in optically denser medium for which angle of refraction in optically less dense medium is 90
Define lens
A piece of clear plastic or glass with curved surface for concentrating or dispersing light rays
Define focal length of converging lens
The distance between optical centre C and principal focal point F (on the principal axis where the rays parallel to the principal axis meet after passing through the lens) - 2m
Define ionising radiation
Radiation that has the energy to remove electrons from atoms or molecules, thereby ionising them
Define wave
A wave is a disturbance that propagates through space, transferring energy with it but not matter
Define transverse wave
A transverse wave has a direction of vibration that is perpendicular to direction of wave travel
Define longitudinal waves
A longitudinal wave has direction of vibration parallel to direction of wave travel
Define amplitude of wave
The maximum displacement of a point from its rest position
Define wavelength
The shortest distance between any two points of a wave which are in a phase
Define displacement-distance graph
A plot of displacements of all points of a wave at an instant
Define period of wave
The time taken to produce one complete wave
Define frequency of wave
The number of complete waves produced per unit time
Define wave speed
The distance travelled by the wave per unit time
Define wavefront
An imaginary line on a wave that joins all adjacent points that are in phase
Define sound
A longitudinal wave travelling in a medium, created by a vibrating source
Define echo
The repetition of sound due to the reflection of sound
Define ultrasound
Ultrasound is sound with frequencies above the upper limit of the human range of audibility
Define speed
Speed is the distance travelled per unit time
Define velocity
Velocity is the rate of change in displacement
Define average speed
Average speed assumes an object moves at same speed throughout entire distance
Define instantaneous speed
Speed of an object at a particular instant
Define acceleration
The rate of change of velocity
Define scalar quantity
Physical quantities that only have magnitude
Define vector quantity
Physical quantities that have both magnitude and direction
Define mass
A measure of the amount of matter in a body
Define weight
The gravitational force acting on an object that has mass
Define gravitational field
A region in which mass experiences a force due to gravitational attraction
Define gravitational field strength
The gravitational force per unit mass placed at that point
Define inertia
Inertia of an object is the reluctance of the object to change its state of rest or motion due to its mass
Define friction
Friction is the contact force that opposes or tends to oppose motions between surfaces in contact
Define moment of a force
The product of the force and perpendicular distance from the pivot to the line of action of the force
Define centre of gravity
The point at which the weight of the object appears to act
Define stability
The ability to return to its original position after it is slightly displaced
Define internal energy of a substance
The sum of kinetic energy due to the random motion of particles and potential energy due to forces of attraction between the particles
Define kinetic energy
Kinetic energy is the energy a body possess due to its motion
Define gravitational potential energy
The energy a body possess due to its position relative to a reference level, usually the ground.
Define work done
Energy transferred mechanically by force acting over a distance
Define power
Power is rate of work done or rate of energy transfer
Define density
Density of a substance is its mass per unit volume
Define pressure
Force acting per unit area
Define heat capacity
The amount of heat required to raise the temperature of a substance by 1K or 1C
Define specific heat capacity
Specific heat capacity is the amount of heat required to raise the temperature of a unit mass of a substance by 1K or 1C
Define melting
The change from solid state to liquid state when energy is transferred to the substance. During this process, temperature of pure substance remains constant
Define boiling
Boiling is change from liquid state to gaseous state when energy is transferred to the substance. During the process, temperature of a pure substance remains constant
Define latent heat
The energy released or absorbed to change the state of a substance at a constant temperature
Define latent heat of fusion/vapourisation
The amount of heat required/released to change a substance between the solid/liquid and liquid/gas states, at constant temperature
Define specific heat of fusion/vapourisation
The amount of heat required/released to change a unit mass of substance between solid/liquid and liquid/gas states, at constant temperature
