Physics Definitions Flashcards
Learn them off (34 cards)
A Real Image
A real image is an image that is formed by the actual intersection of rays. It can be formed on a screen.
A Virtual Image
A virtual image is an image formed by the apparent intersection of rays. It cannot be formed on a screen.
Conduction
Conduction is the transfer of heat energy through a substance by the passing on of molecular vibration from molecule to molecule without any overall movement of the substance.
Convection
Convection is the transfer of heat through a fluid by means of circulating currents of fluid caused by the heat.
Cornea
The cornea together with the lens form part of the focusing system.
Critical Angle
The critical angle is the angle of incidence whose angle of refraction is 90° when light travels from a denser to a rarer medium.
Total Internal Reflection occurs when angle of refraction is greater than the critical angle.
Diffuse Reflection
Diffuse Reflection occurs when light hits a matt surface and the reflected light is scattered in all directions.
Heat
Heat is a form of energy. It is the energy due to the movement of the molecules within a body.
Heat Capacity
The heat capacity of an object is the amount of heat energy needed to change its temperature by 1K.
SI unit is the joule per kelvin (J/K)
Laws of Reflection
1: The incident ray, the normal at the point of incidence and the reflected ray all lie on the same plane.
2: The angle of incidence is equal to the angle of reflection.
Laws of Refraction
1: The incident ray, the normal at the point of incidence and the refracted ray all lie on the same plane.
2 (Snell’s Law): The ratio of the sine of the angle of incidence to the sine of the angle of refraction is a constant.
Optic Nerve
The optic nerve carries the information in electrical form to the brain.
Power of Accommodation
The power of accommodation is the eye’s ability to focus a real image of an object on the retina, whether the object is near to or far from your eye.
Reflection
Reflection is the bouncing of light from the surface of an object.
Refraction
Refraction is the bending of light as it travels from one transparent medium to another with a different refractive index.
Refractive Index
The refractive index of a material is the ratio of the sine of the angle of incidence to the sine of the angle of refraction when light travels from air into that material.
Retina
The retina is a ligth sensitive screeen a the back of the eye. When light strikes the retina, electrical signals are sent to the brain. The result of this is sight.
Stationary Wave
When two periodic travelling waves of the same frequency and amplitude moving in opposite directions meet, they interfere with each other to form a stationary wave.
Temperature
Temperature is the measure of hotness or coldness of a body.
Thermometric Property
A thermometric property is any physical property that changes measurably with temperature.
Total Internal Reflection
Total Internal Reflection occurs when light going from a denser to a rarer medium strikes the rarer medium at an angle greater than the critical angle. The light does not enter the second medium, it is all reflected back into the denser medium.
Mechanical Waves
A Travelling Mechanical Wave is a disturbance carrying energy through a medium without any overall movement of that medium.
E.g. Water waves, Sound waves, Waves on a rope, Ultrasound waves
Electromagnetic Waves
Electromagnetic waves are energy transmitted from one place to another at the Speed of Light.
They do not need a medium.
Specific Heat Capacity
The specific heat capacity of a substance is the heat energy needed to change the temperature of 1kg of that substance by 1K.
SI unit is the joule per kilogram per kelvin ( J/kg/K)
