Current is the rate of flow of charges.
Month: November 2023
Define electrostatic charging by friction.
Electrostatic charging by friction is a process in which surface electrons are transferred from one electrical insulator to another electrical insulator when the insulators are rubbed together.
Define electric field.
An electric field is a region in which charged particles experience an electric force.
Define echo.
An echo is a reflected sound wave bouncing off hard surfaces.
Define ultrasound.
Ultrasound is a sound which has the frequency above human hearing range, above 20 000 Hz.
List the components of electromagnetic waves, from the lowest frequency to highest frequency.
Radio waves, Microwaves, Infrared rays, Visible light rays (ROYGBIV), Ultraviolet rays, X-rays, Gamma rays.
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List the properties of electromagnetic waves.
- They transfer energy from a wave source
- They are transverse waves
- They travel with the same speed of 3×108 m/s in vacuum
- They can travel through vacuum. No medium required for its transmission.
- They travel in straight lines.
Define focal length.
Focal length is the distance between the optical centre and the focal point.
State the two conditions needed for total internal reflection to occur.
- The light ray is travelling from a denser optical medium to a less dense optical medium.
- The angle of incidence in the denser medium is greater than the critical angle of the medium.
Define total internal reflection.
Total internal reflection occurs when the angle of incidence in the optically denser medium is greater than the critical angle, causing the light ray to be reflected in the denser medium, and no light ray being refracted.