Physics chapter 15

Question 1

How is a rainbow formed?

Answer 1

When white light is bent while entering a droplet of water. split into separate colors and reflected back.

Question 2

What does Infra mean?

Answer 2

Below or Lower down

Question 3

Define the term electromagnetic spectrum?

Answer 3

The term used by scientists to describe the entire range of light that exists.

Question 4

What is the realtionship between the intensity of a radiation and its wavelength?

Answer 4

The higher the intensity the shorter the wavelength and the higher the energy.

Question 5

Which visible radiation has the shortest wavelength?

Answer 5

Indigo

Question 6

Which visible radiation has the longest wavelength?

Answer 6

Red

Question 7

What does the solar energy reaching earths surface include?

Answer 7

It includes visible lights, ultraviolet and infrared radiation

Question 8

What are damages that can be caused by ultraviolet light?

Answer 8

Ultraviolet light is high energy and causes damage including sunburn , fading of pigments and degradation of compounds such as fabrics, plastic and ruber.

Question 9

What is the relationship between wavelength and the danger of the wave?

Answer 9

The shorter the wavelength / higher the frequency the more damaging the wav will be.

Question 10

What happens to most of the short-waved radiating from the sun?

Answer 10

Most of it is absorbed by the ozone layer, hence very little reaches the earth.

Question 11

What are the seven types of waves under the electromagnetic spectrum?

Answer 11

1. Radio waves
2. Microwaves
3. Infrared waves
4. Visible light
5. Ultraviolet
6. X rays
7. Gamma rays

Question 12

What is the speed of electromagnetic waves in a vacuum?

Answer 12

300,000,000 m/s

Question 13

Define monochromatic?

Answer 13

Light of a single colour.

Question 14

Define polychromatic light?

Answer 14

Polychromatic light composed of more than one wavelength, exhibiting many colors.

Question 15

Which light travels faster in glass, violet or red ligh?

Answer 15

Red light due to its longer wavelength

Question 16

Which travels faster in a vacuum, violet or red light?

Answer 16

They both travel at the same speed in a vacuum.

Question 17

How does an X-ray show items behind an object?

Answer 17

Bones absorb x-rays more strongly than flesh and so they appear as shadows in images.

Question 18

Name and explain one use of gamma rays?

Answer 18

They gamma rays can be used to detect the presence of cancer and to kill the cancerous cells using a beam of gamma rays.

Question 19

Define the use of radio waves?

Answer 19

.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.

Question 20

What is the range of size of microwaves of cell phones and satellites?

Answer 20

1 cm to 20 m

Question 21

Define use of Microwave ablation?

Answer 21

Used in treatment of liver tumor

Question 22

Define Microwaves diathermy?

Answer 22

Used in pain managment

Question 23

Define Transurethral microwave?

Answer 23

Thermotherapy is used in treatment of lower urinary tract syndrome

Question 24

What is the range of frequency of Infrared waves?

Answer 24

300GHz to 400GHz

Question 25

What is the most sued wavelength by artificial satellites?

Answer 25

Microwaves

Question 26

How low can low Earth orbits get?

Answer 26

As low as 2000km above the earths surface.

Question 27

Define bluetooth?

Answer 27

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.

Question 28

Define analogue signal?

Answer 28

A signal which varies continuously in frequency and amplitude

Question 29

Define digital signal?

Answer 29

A signal that consists of a series of pulses which are either on or off

Question 30

Name 2 types of electromagnetic waves which are useful for cooking foods?

Answer 30

Microwaves and Infrared radiation

Question 31

Explain how radio waves, microwaves and infrared radiation might all play a part when you watch a television show?

Answer 31

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.

Question 32

Define ultra violet radiation.

Answer 32

Electromagnetic radiation with a wavelength shorter than that of visible light

Question 33

Function of regenerators in transmitting digital signals?

Answer 33

Regenerators clean up the signal to remove distortions and also boosts the signal if it has been weakened

Question 34

What is a DAC?

Answer 34

A Digital to Analogue Converter

Question 35

What is a ADC?

Answer 35

Analogue to Digital Converter

Question 36

What is one of the uses of UV light?

Answer 36

.It is used by forensics scientists to find evidence at crime scenes.
.It is also used to sterilise water

Question 37

Why is UV light used in crime scenes?

Answer 37

Because it causes some chemicals to emit visible light such as saliva, sweat and other body fluids.

Question 38

Why is UV used to sterilise water?

Answer 38

The long exposure to UV light breaks down the DNA in bacteria and viruses that are in the water. Making it safer to drink.

Question 39

What is one purpose of infrared radiation?

Answer 39

It is used in remote controls for devices such as televisions.