physics definitions

Accuracy

the degree of closeness of measurements od qauntity to that quantity’s actal value

presicion

the degree to which repeated measurement under unchanged conditions show the same results.

Reliability

the repeatability and consistency of a test

validity

the strength of the final results and whether they can be regarded as accurately describing the real world

Current

rate of flow of charge

resistance

a material’s opposition to the flow of an electrical current

coulomb

• one coulomb is the amount of charge

• passing a cross-section

• of a conductor in one second

• when current is one ampere

Potential difference

the work done per unit positive charge

Emf

total energy supplied per coulomb of charge by a cell

Ohm’s Law

• current through a conductor

• is directly proportional to the potential difference

• across the conductor

• at a constant temperature

Ohm

• A conductor has a resistance of 1 ohm

• if the current is 1 ampere

• when a potential difference of 1 volt

• is maintained between its ends.

Field

A region in space in which a force is experience

Gravitational Field

A region in space where an object of mass experiences a force

Magnetic field

A region in space where a magnetic object experiences a force

Electrostatic Field

A region in space where a charged object experiences a force

Weight

The gravitational force the earth exerts on any object in or near its surface

Mass

amount if matter that an object has

newton’s law of universal gravitation

• every particle with mass in the universe

• attracts every other particle with a force

• which is directly proportional to the product of their masses

• and inversely proportional to the square of the distance between their centres

Principle of quantisation of charge

every charge is a multiple of an electron charge

Principle of conservation of charge

the net charge if an isolated system remains constant

wave

means by which energy us transformed from one point in a medium to another

Diffraction

bending of waves around an object in its path

Amplitude

maximum displacement of the wave from the mean position

Frequency

number of vibrations passing a fixed point in a given amount of time

Electromagnetic wave

• Wave of energy consisting of electric and magnetic fields

• oscillating at right angles to each other

• produced by acceleration of a electric charge

angle of incidence

the angle between the incident ray and the normal to the surface

angle of reflection

the angle between the normal and the reflected ray

pulse

a single disturbance

ray

direction in which the wave moves

superposition

when 2 sets of circular waves meet and cross

an interference pattern forms

vector

a physical quantity that has both magnitude and direction

resultant vector

the single vector which has the same effect as the original vector acting together

scalar

a physical quantity that has magnitude and direction

distance

the length of path travelled

displacement

the change in position

velocity

the rate of change of displacement

acceleration

the rate of change of velocity

gravitational potential energy

the energy an object possesses due to its position relative to a point

kinetic energy

the energy an object has as a result of the objects motion

mechanical energy

the sum of gravitational potential and kinetic energy at a point

law of conservation of energy

the total energy in a system cannot be destroyed or created, only transformed from one form to another

the principal of conservation of mechanical energy

in the absence of air or any other external forces, the mechanical energy of an object is constant