- Interference: ability of two or more waves to reinforce or cancel each other.
- Constructive interference occurs when two wave motions reinforce each other, resulting in a wave of greater amplitude.
- What determines the type of electromagnetic radiation emitted by the Sun, stars, and other astronomical objects? Temperature
- Electromagnetic radiation is emitted when electric charges accelerate, changing either the speed or the direction of their motion.
- The hotter the object, the faster the atoms move in the object, jostling one another, colliding with more electrons, changing their motions with each collision.
- Each collision results in the emission of electromagnetic radiation- radio, infrared, visible, ultraviolet, x-rays. How much of each depends on the temperature of the object producing the radiation.
Measuring Temperature - Atoms and molecules that make up matter are in constant random motion.
- Temperature is a direct measure of this internal motion.
- The higher the temperature, the faster (on average) the random motion of particles in matter.
- Temperature of an object represents the average thermal energy of particles that make up that object.
TWO MAJOR SCALES °F and °C - Fahrenheit scale based on temperature that salt water freezes 0°F (lower than pure water).
- Related to Celsius (or Centigrade) by the formula:
- F = 9/5 C + 32
- C = 5/9(F - 32).
ABSOLUTE SCALE K AND °C - Celsius (originally Centigrade) based on freezing and boiling point of pure water, chosen to be 0°C and 100°C
- Kelvin based on absolute coldest temperature possible (absolute zero)
- Related by
- K = C – 273.15
- C = K + 273.15
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