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definitions
Term | Definition |
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The incident ray | The incident ray, the normal at the point of incidence and the refracted ray all lie on the same plane. |
The angle of incidence | The angle of incidence and the angle of refraction are equal. |
The incident ray | The incident ray, the normal at the point of incidence and the refracted ray all lie on the same plane. The ratio of the sine of the angle of incidence to the sine of the angle of refraction is a constant for a given two media. (Snell's Law) |
Refractive Index | The Refractive Index between two media is the ratio of the sine of the angle of incidence to the sine of the angle of refraction when light travels from one of those media to the other. |
Critical Angle | The Critical Angle of a medium is the angle of incidence when the angle of refraction is 90°.It occurs only when light is going from a more dense to a less dense medium |
Total Internal Reflection | When the angle of incidence in the denser medium is greater than the critical angle, it is refracted back into the dense medium, which is known as Total Internal Reflection |
Transverse Wave | A Transverse Wave is a wave where the direction of vibration is perpendicular to the direction of wave motion. |
Longitudinal Wave | A Longitudinal Wave is a wave where the direction of vibration is parallel to the direction of wave motion. |
Reflection of waves | The bouncing of waves off an obstacle in their path is called Reflection of waves. |
Refraction | The changing of direction of a wave when it enters a region where its speed changes is called Refraction. |
Diffraction | The sideways spreading of waves into the region beyond a gap or around an obstacle is called Diffraction. |
Interference of Waves | When waves from two coherent sources meet, a new wave is produced. The amplitude at any point along this wave is the algebraic sum of the individual wave. This is known as Interference of Waves. |
Stationary Waves | Stationary Waves are produced when two waves of the same frequency, wavelength and amplitude moving in opposite directions meet. They interfere with each other producing a stationary wave. |
Polarisation | Polarisation is confining the vibrations to one plane only. Only Transverse waves can be polarised. |
Doppler Effect | The apparent change in frequency due to the relative motion between the source and the observer is called the Doppler Effect |
Overtones | Frequencies which are multiples of a certain frequency are called Overtones of that frequency. |
Harmonics | Frequencies which are multiples of the fundamental frequency are called Harmonics |
Loudness | Loudness depends on amplitude. The greater the amplitude the greater the loudness |
Pitch | Pitch of a note depends on frequency. The higher the frequency the higher the pitch. |
Quality | Quality of a note depends on the number of overtones present in the note and their relative strengths |
Resonance | Resonance is the response of a body to a frequency equal to that of its own natural frequency. |
Sound Intensity at a point | Sound Intensity at a point is the rate at which sound energy is passing per second through an area of 1 m2atright angles to the direction in which the sound is travelling. |
Frequency Limits of Audibility | Frequency Limits of Audibility are the highest and lowest frequencies that can be heard by a normal human ear –(20Hz to 20,000Hz) |
Sound intensity | Sound intensity at a point is the rate at which sound energy is passing per second through an area of 1 m2at right angles to the direction in which the sound is travelling. |
Threshold of Hearing | Threshold of Hearing is the smallest sound intensity detectable by the average human ear at a frequency of 1kHz = 1x10-12Wm-2. |
Fundamental Frequency | Fundamental Frequency of a string is when the string is vibrating with an antinode at its center and a node at each end |
Grating Constant | Grating Constant is the distance between two adjacent slits |
Dispersion | Dispersion is the splitting of white light into its component colours. |
Secondary Colour | Secondary Colour is the colour formed by mixing two primary colours in equal intensity |
Displacement | Displacement is distance in a given direction |
Speed | Speed is the rate of change of distance with respect to time |
Velocity | Velocity is the rate of change of displacement with respect to time. |
Acceleration | Acceleration is the rate of change of velocity with respect to time. |
Scalar | A Scalar is a quantity that has magnitude only |
Vector | A Vector is a quantity that has magnitude and direction. |
Force | A Force is anything that causes the velocity of an object to change. (Speed up, slow down or change direction)OR Force is equal to the rate of change of momentum. |
Friction | Friction is the force that tries to prevent one surface sliding over another. |
Mass | A Mass of a body is a measure of how difficult it is accelerate that body. |
Weight | Weight is the product of mass by acceleration due to gravity |
1 Newton | 1 Newton is the force that gives a mass of 1kg an acceleration of 1m/s2 |
Newton’s 1st Law | Newton’s 1stLawstates that every body will remain at rest or travelling with a constant velocity unless an external force acts on it. |
Newton’s 2nd Law | Newton’s 2ndLawstates that when an external force acts on a body the rate of change of the body’s momentum is directly proportional to the force and takes place in the direction of the force. |
Newton’s 3rdLaw | Newton’s 3rdLaw states that to every action there is an equal and opposite reaction. |
Terminal Velocity | Terminal Velocity is where air resistance R is equal and opposite to the weight of the skydiver. |
Momentum | Momentum is the product of mass and velocity |
Principle of Conservation of Momentum | The Principle of Conservation of Momentum states that in any interaction between two or more bodies, the total momentum before the interaction is equal to the total momentum after the interaction provided no external forces act on the bodies. |
Angular Velocity | Angular Velocity is the rate of change of angleθwith respect to time |
Centripetal Force | Centripetal Force is the force needed to keep a body moving in a circle. Its direction is towards the centre of the circle. |
Centripetal Acceleration | Centripetal Acceleration is the acceleration needed to keep a body moving in a circle. Its direction is towards the centre of the circle. |
Period of Orbit | Period of Orbit is the time taken for a satellite to go once round the central body OR the time taken for one complete revolution. |
Angular speed | Angular speedω is the angle turned through per second |
Newton’s Law of Gravitation | Newton’s Law of Gravitation states that any two point masses in the Universe attract each other with a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between them. |
Gravity | Gravity is the acceleration with which objects near the earths surface will fall if placed in a vacuum. |
Weight | he Weight of an object is the force of the Earths gravity acting on it. |
Density | Density of a substance is its mass per unit volume. |
Pressure | Pressure is force per unit area. |
Pascal | The pressure is equal to 1 Pascal if it causes a force of 1 Newton when applied over an area of 1 m2. |
Archimedes’s Principle | Archimedes’s Principle states that when an object is partially or completely immersed in a fluid it experiences an upthrust equal in magnitude to the weight of the fluid displaced. |
Law of Flotation | Law of Flotation states that when an object floats in a fluid it experiences an upthrust which is equal to the weight of the of the displaced fluid. |
Boyle’s Law | Boyle’s Law states that for a fixed mass of gas at constant temperature pressure is inversely proportional to volume. |
Moment of a force | Moment of a force about an axis is equal to the magnitude of the force multiplied by the perpendicular distance from the force to the axis. |
Equilibrium | A body is in Equilibrium if the sum of the forces is zero and the sum of the moments about any point is zero. |
Couple | A Couple is 2 forces of equal magnitude acting in opposite directions. |
Hooke’s Law | Hooke’s Lawstates that when an object is bent, stretched or compressed by a displacement s, the restoring force Fis directly proportional to the displacementprovided the elastic limit is not exceeded. |
Simple Harmonic Motion | A body is said to moving with Simple Harmonic Motionif its acceleration is directly proportional to its distance from a fixed point on its path and its acceleration is always directed towards that point. |
Work | When a force moves a body through a displacement in the direction of the force, the Workdone is equal to the product of the force and displacement. |
1 Joule | 1 Jouleis the work done when a force of 1 Newton acts for a distance of 1 Metre in the direction of the force. |
Energy | Energy is the ability to do work. |
Principle of Conservation of Energy | The Principle of Conservation of Energystates that energy cannot be created or destroyed but can only be changed from one form to another. |
Kinetic Energy | Kinetic Energyis the energy of a body due to motion. |
Potential Energy | Potential Energyis the energy of a body due to position |
Renewable Energy | Renewable Energyis a source of energy that does not get used up. |
Power | Poweris the rate of doing work ORthe rate at which energy is converted from one form to another. |