AS level Physics Definitions (CIE)
Conditions for interference
2 waves meet Waves have a constant phase difference
Newtons First Law
A body continues in a state of rest or constant velocity unless acted upon by a resultant force
Antinode
A point of maximum amplitude on a standing wave
Node
A point of zero amplitude on a standing wave
Mass
A property of a body that resists change in motion
Electric Field
A region in which a charged body experiences a force
Progressive wave
A wave that transfers energy as a result of vibrations
Distinguish between accuracy and precision
Accuracy is determined by the closeness of the measurement to the true value while precision is determined by the range in values
elastic collision
Both momentum & kinetic energy of the system are conserved
Coherence
Constant phase difference between the two waves
displacement
Distance moved in a certain direction from start to end point
speed
Distance travelled per unit time
Kinetic energy
Energy a mass has due to motion
Gravitational Potential energy
Energy of a mass due to its position in a gravitational field
Elastic potential energy
Energy stored in an object due to a force changing it shape
Newtons Third Law
Every action has an equal and opposite reaction
The principle of moments
For a body of equilibrium, the sum of all the anti-clockwise moments about a point must be equal to the clockwise moments about that same point
Principle of conservation of momentum
For a system of interacting bodies, the total momentum remains constant provided there is no resultant force acting on the system
Hooke's Law
Force is proportional to extension provided the proportionality limit is not exceeded
Electric Field Strength
Force per unit positive charge
Kirchhoff's second law
In a closed circuit, the sum of e.m.f's is equal to the sum of p.d's
Volt
Joule per coulomb
Frequency of a source
Number of oscillations per unit time from the source of the wave
Inelastic collision
Only momentum is conserved, total kinetic energy is not conserved
Difference between p.d and emf in terms of energy transformations
Potential difference (p.d.) is the energy transformed from electrical to other forms, per unit charge. Electromotive force (e.m.f.) is the energy transformed from other forms to electrical per unit charge.
Internal resistance
Resistance in the battery causing loss of volts
Interference
Same as superposition
Coloumb
The charge of an ampere second
Accuracy
The closeness of measurement values to the true values
Ohms law
The current in a metallic conductor is directly proportional to the potential difference across its ends, provided its temperature remains constant
Precision
The degree of agreement between several measurements of the same quantity and is determined by the range of the values
Displacement of a wave
The distance of a point on wave above or below the equilibrium position
Weight
The effect of gravitational field on a mass
Electric current
The flow of charge carriers
Stress
The force per cross-sectional area
Amplitude
The maximum distance of a particle in wave measured from the equilibrium position
Wavelength
The minimum distance between two adjacent crests or troughs
Frequency of a progressive wave
The number of wavefronts passing a point per unit time
Doppler effect
The observed frequency is different to the source frequency when the source moves relative to the observer
Elastic limit
The point beyond which a material does not return to its original length when the load is removed
Centre of Gravity
The point through which the entire weight of a body may be considered to act
the torque of a couple
The product of one of the forces of a couple and the perpendicular distance between the forces.
moment
The product of the force and the perpendicular distance of its line of action to the pivot
Strain
The ratio of extension (change in length) to original length
Electrical Resistance
The ratio of potential difference across a component to the current flowing throw it
Youngs Modulus
The ratio of stress to strain
Efficiency
The ratio of useful energy output from the system to the total input energy
Ohm
The resistance of 1 volt per ampere
Newtons Second Law
The resultant force is equal to the rate of change of momentum and acts in the direction of it.
Speed of a wave
The speed at which energy is transferred/ speed of a wavefront
electromotive force
The total energy transferred by a source in driving a unit charge round a complete circuit
Longitudinal wave
The vibration of particles is parallel to the direction of propagation of energy
Transverse wave
The vibration of particles is perpendicular to the direction of propagation of energy
distance
Total length covered irrespective of the direction of motion
Diffraction
When a wavefront is incident on a gap, the wave spreads
Principle of superposition
When two waves meet, the resultant displacement is the algebraic sum of the individual displacements
Explain the formation of a stationary wave
When two waves, having the same frequency and wavelength, traveling in opposite directions meet, the resultant displacement is the sum of the individual displacements of the waves, and produces node and antinodes
Scalar
a quantity that has a magnitude only
Vector
a quantity that has both magnitude and direction
Kirchhoff's first law
the algebraic sum of currents entering a junction is zero.
pressure
the force per unit area
density
the mass per unit volume
Work Done
the product of force and displacement in the direction of the force
Linear momentum
the product of mass and velocity
Impulse
the product of the force and the time during which the force acts
velocity
the rate of change of displacement
force
the rate of change of momentum
acceleration
the rate of change of velocity
Systematic error
the type of error that causes readings to deviate in one direction from the true value
Random error
the type of error which causes readings to scatter about the true value
Potential difference
the work done per unit charge
power
the work done per unit time