Physics chapter 15 Flashcards
How is a rainbow formed?
When white light is bent while entering a droplet of water. split into separate colors and reflected back.
What does Infra mean?
Below or Lower down
Define the term electromagnetic spectrum?
The term used by scientists to describe the entire range of light that exists.
What is the realtionship between the intensity of a radiation and its wavelength?
The higher the intensity the shorter the wavelength and the higher the energy.
Which visible radiation has the shortest wavelength?
Indigo
Which visible radiation has the longest wavelength?
Red
What does the solar energy reaching earths surface include?
It includes visible lights, ultraviolet and infrared radiation
What are damages that can be caused by ultraviolet light?
Ultraviolet light is high energy and causes damage including sunburn , fading of pigments and degradation of compounds such as fabrics, plastic and ruber.
What is the relationship between wavelength and the danger of the wave?
The shorter the wavelength / higher the frequency the more damaging the wav will be.
What happens to most of the short-waved radiating from the sun?
Most of it is absorbed by the ozone layer, hence very little reaches the earth.
What are the seven types of waves under the electromagnetic spectrum?
- Radio waves
- Microwaves
- Infrared waves
- Visible light
- Ultraviolet
- X rays
- Gamma rays
What is the speed of electromagnetic waves in a vacuum?
300,000,000 m/s
Define monochromatic?
Light of a single colour.
Define polychromatic light?
Polychromatic light composed of more than one wavelength, exhibiting many colors.
Which light travels faster in glass, violet or red ligh?
Red light due to its longer wavelength
Which travels faster in a vacuum, violet or red light?
They both travel at the same speed in a vacuum.
How does an X-ray show items behind an object?
Bones absorb x-rays more strongly than flesh and so they appear as shadows in images.
Name and explain one use of gamma rays?
They gamma rays can be used to detect the presence of cancer and to kill the cancerous cells using a beam of gamma rays.
Define the use of radio waves?
.Radio waves are used to broadcast radio and television signals.
.RFID (Radio frequency identification) chips are also used everywhere as tags to store and share data.
What is the range of size of microwaves of cell phones and satellites?
1 cm to 20 m
Define use of Microwave ablation?
Used in treatment of liver tumor
Define Microwaves diathermy?
Used in pain managment
Define Transurethral microwave?
Thermotherapy is used in treatment of lower urinary tract syndrome
What is the range of frequency of Infrared waves?
300GHz to 400GHz
What is the most sued wavelength by artificial satellites?
Microwaves
How low can low Earth orbits get?
As low as 2000km above the earths surface.
Define bluetooth?
It is used for short-range communication and uses radio waves. The signals weaken when they pass through a wall and are useful for communication between electronic devices.
Define analogue signal?
A signal which varies continuously in frequency and amplitude
Define digital signal?
A signal that consists of a series of pulses which are either on or off
Name 2 types of electromagnetic waves which are useful for cooking foods?
Microwaves and Infrared radiation
Explain how radio waves, microwaves and infrared radiation might all play a part when you watch a television show?
The microwaves are used to transfer signals from the satellite, the radio waves are used to broadcast the footage, and the remote control uses infrared radiation.
Define ultra violet radiation.
Electromagnetic radiation with a wavelength shorter than that of visible light
Function of regenerators in transmitting digital signals?
Regenerators clean up the signal to remove distortions and also boosts the signal if it has been weakened
What is a DAC?
A Digital to Analogue Converter
What is a ADC?
Analogue to Digital Converter
What is one of the uses of UV light?
.It is used by forensics scientists to find evidence at crime scenes.
.It is also used to sterilise water
Why is UV light used in crime scenes?
Because it causes some chemicals to emit visible light such as saliva, sweat and other body fluids.
Why is UV used to sterilise water?
The long exposure to UV light breaks down the DNA in bacteria and viruses that are in the water. Making it safer to drink.
What is one purpose of infrared radiation?
It is used in remote controls for devices such as televisions.
