P1 - topic 2 - visible light, UV, X-rays

Question 1

why do we see objects?

Answer 1

because they either give out or reflect light - they’re illuminated

Question 2

When light enters your eye, what happens?

Answer 2

light gets refracted through the lens and focused onto the retina at the back of the eye. The retina sends messages to the brain and the brain interprets them

Question 3

How do cameras work?

Answer 3

use a lens to focus visible light onto a light sensitive film or electronics sensor that records the image

Question 4

What controls how much light enters the camera?

Answer 4

The Lens aperture

Question 5

What does the shutter speed on a camera determine?

Answer 5

how long the film or sensor is exposed to the light

Question 6

What two things control how much light the photographer can capture

Answer 6

shutter speed

Aperture

Question 7

what radiation is used to detect forged bank notes?

Answer 7

ultra violet

Question 8

what is a property of certain chemicals?

Answer 8

florescence

Question 9

why are things fluorescent?

Answer 9

ultraviolet radiation is absorbed and then visible light is emitted

Question 10

why do bank notes print special marking in fluorescent ink of their bank notes?

Answer 10

to detect forgeries

Question 11

how can you tell the difference between a genuine bank not and a fake bank note?

Answer 11

using a ultra violet light,
genuine notes will display the special fluorescent markings
fake notes will glow all over and there’ll be no markings

Question 12

on fake bank notes why do they glow all over and show no markings when under a UV light?

Answer 12

they are often printed on cheaper paper that’s slightly fluorescent

Question 13

How do fluorescent lamps use UV radiation?

Answer 13

they use it to emit visible light

Question 14

why are fluorescent lamps safe to use?

Answer 14

all the UC radiation is absorbed by a phosphor coating on the inside of the glass

Question 15

Why are security pens used?

Answer 15

to mark your property with your name

Question 16

how do security pens work?

Answer 16

the ink in the pen is only visible in UV light so it can help the police identify your property of its stolen

Question 17

Why is UV radiation used to disinfect water?

Answer 17

the UV kills off any viruses and bacteria in the water to make it safe to use

Question 18

What are the four main uses of UV radiation?

Answer 18

Bank notes
Fluorescent lamps
Security pens
Disinfect water

Question 19

what are X rays used for?

Answer 19

looking inside objects

Question 20

what do radiographer a on hospitals do?

Answer 20

take X ray photographs of people to see if they have any broken bones

Question 21

why do we need viable light?

Answer 21

so that we can see

Question 22

what do X rays pass through easily?

Answer 22

flesh

Question 23

what do X rays not travel through easily?

Answer 23

more dense materials than flesh like bones or metal

Question 24

what give you an X Ray image?

Answer 24

the amount of radiation that’s absorbed or not absorbed

Question 25

what can X rays cause?

Answer 25

cancer

Question 26

what do radiographers do to prevent them from cancer?

Answer 26

wear lead aprons and stand behind a lead screen or leave the room to keep their exposure to X rays to a minimum

Question 27

why do airport security use X rays?

Answer 27

to scan luggage to check for suspicious-looking objects

Question 28

why do airports use low-level X rays?

Answer 28

because they aren’t as harmful as the X rays used in hospitals