Electromagnetic Waves

Question 1

What type of waves are electromagnetic waves?

Answer 1

-they are transverse waves meaning they oscillate perpendicular to the direction of energy transfer.

Question 2

What is the equation linking wavespeed, wavelength and frequency?

Answer 2

-wave speed= frequency (Hz) x wavelength

Question 3

What speed do electromagnetic waves travel in a vacuum?

Answer 3

3 x 10 to the power of 8 m/s

Question 4

How do electomagnetic waves travel in at different speeds?

Answer 4

-in different mediums, they travel at different speeds.
-this causes refraction.

Question 5

What are the electromagnetic waves in order from left to right?

Answer 5

-radio waves
-micro waves
-infrared
-visible light
-ultra violet
-x-rays
-gamma rays

Question 6

What differentiates the elctromagnetic waves and how does it differ going from left to right?

Answer 6

-wavlength and frequency
-frequency increases from left to right.
-wavelength decreases from left to right.

Question 7

What are our eyes able to detect in the electromagnetic spectrum?

Answer 7

-we can only see visible light.

Question 8

Which of the elctromagnetic waves are ionising?

Answer 8

-ultraviolet, x-rays, gamma rays

Question 9

Which of the elctromagnetic waves are used in communication?

Answer 9

-radio waves and microwaves

Question 10

Where do electromagnetic waves come from?

Answer 10

-gamma rays come from radioactive decay.
-visible light, ultraviolet and x-rays are emitted when electrons drop down energy levels.
-infra red is generated when bonds holding molecules together vibrate.

Question 11

What happens when electromagnetic waves come into contact with something?

Answer 11

-reflected
-absorbed
-transitted

Question 12

What are the two uses of microwaves?

Answer 12

-the type of microwaves that are absorbed by water molecules are used to heat our food.
-the water molecules absorb the microwaves causing water molecules in the food to vibrate more and therefore heat up due to conduction.
-the type of microwaves that are not absorbed by water molecules are used by satellites.
-the signal from a transmitter is transmitted into space and when picked up by the reciever, it is transmitted back to Earth in a different direction and is received by a satellite dish.

Question 13

Where is infra red radiation emitted?

Answer 13

-emitted from all objects that have thermal energy.
-the hotter the object, the more infra red radiation it will give.

Question 14

What do we use infrared radiation for?

Answer 14

-used in infra red camera to see in the dark.
-therefore, we can spot living orgnaisms as they are warm and therefore appear brighter.
-also used in cooking,emits lots of infrared radiation and heats our food by transferring heat energy.
-used in electrical heaters, electrical energy hearts the metal and emits infrared radiation to surroundings.

Question 15

Why is infrared radiation not used in microwaves?

Answer 15

-the infrared radiation doesn’t penetrate the surface.
-that is why bread toasts in a toaster rather than getting generally warmer.

Question 16

How are microwaves and infra red radiation harmful?

Answer 16

-they are only harmful in high quantities.
-that’s why if you put your hand in a toaster, it will burn.

Question 17

How is visible light used in communication?

Answer 17

-through optical fibre communication.
-optical fibres are thin glass/plastic that are able to transmit pulses of light over long distances because the light is reflected back and forth until it emerges at the other end of the fibre to be interpreted.
-they encode data and information into the light pulses, and is therefore able to be transmitted quickly.

Question 18

How is ultraviolet emitted?

Answer 18

-from the sun causing sun tan.
-or through artificial ways like sun beds.

Question 19

How do fluorescent lights work?

Answer 19

-they generate UV radiation which is absorbed by a layer of phosphorus
and is then re-emitted as visible light.

Question 20

How is UV radiation used in security?

Answer 20

-through security pens, we can write codes that are completely invsible until we shine ultraviolet light on them.
-we do the same with bank notes and passports so they are harder to copy.

Question 21

How is UV radiation used to sterilise water?

Answer 21

-UV radiation destroys microorgansisms.