Question

@nnesha my teacher said some of these are wrong can you help me correct them (4 questions)

Answer 1

@Nnesha

Answer 2

Could you tell me why I did this wrong

Answer 3

@Nnesha

Answer 4

hmm it's larger for sure..

Answer 5

maybe its choice b then instead of C maybe?

Answer 6

yeah but i don't understand why it's not the C
since it's negative the image is behind the mirror

Answer 7

or maybe image distance is not negative

Answer 8

this is what it says in my lesson

Answer 9

\[\rm -6.1=\frac{d_i}{d_o}\]
if d_o is always positive (according to the table) then for this equation image distance needs to be negative

Answer 10

meaning that the answer is B?

Answer 11

I hvae to fill out this table

Answer 12

no i was trying to figure out why it is not C.
BUT if is not C then ofc it is definitely B. other 2 are for smaller

Answer 13

SO would this be the right answer for why it is wrong?

Answer 14

According to this website http://physics.bu.edu/py106/notes/Spherical.html
`When the image distance is positive, the image is on the same side of the mirror as the object, and it is real and inverted. When the image distance is negative, the image is behind the mirror, so the image is virtual and upright. A negative m means that the image is inverted. Positive means an upright image.`

Answer 15

My answer was wrong because I incorrectly came to the conslusion that imageis behind the mirror. The correct answer is that it is large and in front.

Answer 16

I need a reason as to why it is the correct answer :(

Answer 17

\(\color{#0cbb34}{\text{Originally Posted by}}\) @zarkam21
My answer was wrong because I incorrectly came to the conslusion that imageis behind the mirror. The correct answer is that it is large and in front.
\(\color{#0cbb34}{\text{End of Quote}}\)

Answer 18

you think this is good enough

Answer 19

no

Answer 20

If it was me I will put why i Picked the option C in first place. and will ask teacher why it is not C.

Answer 21

this is also part of my lesson

Answer 22

so from this because it is negative wouldnt it be D , because a negative means the image is small and behind the mirror

Answer 23

oh okay one second

Answer 24

no sign doesn't explain if the image is going to be smaller or larger
the number itself will rperesent that

Answer 25

we know that image is 100% larger because 6.1>1

Answer 26

Here is an example of a negative image distance

Answer 27

maybe this will help?

Answer 28

this is about negative mag.

Answer 29

\[\large\rm m=-\frac{d_i}{d_o} \rightarrow -m=\frac{d_i}{d_o}\]
if we move the negative sign then it makes sense that d_i is positive which means the image is in front of the mirror. However if we look at this equation mathematically
if d_o needs to be positive then di must be negative. so I will ask teacher

Answer 30

okay

Answer 31

I will ask the teacher for this one

Answer 32

\[\rm d_o= \frac{-m}{d_i}\] in order to cancel out negative sign di should be negative

Answer 33

or maybe we just have to ignore that

Answer 34

well they are saying I am wrong and I, myself do not understand why . So if you can figure out why I would sppreciate it. If you dont understand what I did wrong either, I will ask the teacher

Answer 35

B is also wrong ??

Answer 36

No no C is

Answer 37

so b is the right answer ?

Answer 38

if it marked C wrong then yeah B needs to be the answer....

Answer 39

OKay sounds good. can we move on to the next one. (There are 4 )

Answer 40

will see. the last time i did these types of question were like years+infinity ago.. but will try

Answer 41

object and image are on the other sides so image distance needs to be negative

Answer 42

opposite sides*

Answer 43

SO prob choice D

Answer 44

what does the red cross mark represent ? i'm confused

Answer 45

the answer is wrong

Answer 46

that is the answer i submitted but it is wrong

Answer 47

that's what i thought but after your comment `so prop D` i got confusd for a second \[\rm m=-\frac{d_i}{d_o}= -\frac{-10 cm}{20cm}\]

Answer 48

-0.5

Answer 49

but i got that wrong

Answer 50

\(\color{#0cbb34}{\text{Originally Posted by}}\) @Nnesha
that's what i thought but after your comment `so prop D` i got confusd for a second \[\rm m=-\frac{d_i}{d_o}= -\frac{-10 cm}{20cm}\]
\(\color{#0cbb34}{\text{End of Quote}}\)
\[\rm m=-\frac{d_i}{d_o}= \color{blue}{-}(\frac{\color{ReD}{-}10 cm}{20cm})\]

Answer 51

ohhhh its 0.5

Answer 52

because of the double negative

Answer 53

yes :=))

Answer 54

yay

Answer 55

would this be a good explanation for why I got it wrong?

My answer was wrong because my calculations were wrong. m=−
di/do=−(-10cm)/(20cm). The answer is 0.50 because of the double negative and I put -0.50

Answer 56

yes you can say that
but my explanation will be different

Answer 57

is this a online class ?

Answer 58

yes it is

Answer 59

what would your explanation be

Answer 60

I don't think your mistake was multiplying two negative values.. You didn't realize that the image distance needs to be negative.
so if it was me i will mention that to my teacher that I couldn't figure out that Di needs to be negative because image and the object are on opposite side
that's how your teacher will understand that you're trying your best but having difficult time to catch the key points maybe she/he will help you with that

Answer 61

Yeah true

Answer 62

shall we continue to the last one

Answer 63

last one ? yayya sure

Answer 64

actually second to last one

Answer 65

there is one more after this

Answer 66

hmm what do you think the answer should be now after figuring out the first question we did together ?

Answer 67

D

Answer 68

D?

Answer 69

well first of all m >1 or m <1 ??

Answer 70

Yes that is true

Answer 71

it is less than

Answer 72

hmm ignore the sign for now

Answer 73

from yesterday post
` when m is negative => the image is inverted`
`when m is positive => the image is upright`
`when m is greater than 1 => image is larger than the object`
`when m is less than 1 => image is smaller than the object``

Answer 74

when m is less than 1 => image is smaller than the object`

Answer 75

thsi is the one we should look at because it is smaller than 1

Answer 76

If i'm not wrong we need to look at sign and the value separately
because they both represent different things

Answer 77

inverted and smaller than

Answer 78

when m is negative => the image is inverted
when m is less than 1 => image is smaller than the object`

Answer 79

m= 2 ignoring the sign
is 2<1 or 2>1 ?

Answer 80

2>1

Answer 81

yes so m is greater than m

Answer 82

okay so fromt hat we can see that it is larger than the object

Answer 83

yes

Answer 84

so choice c

Answer 85

we have one more

Answer 86

yes C because m is negative and di is positive so it should be real image

Answer 87

ohh we did that one yesterday hmm I was confused about that one bec if we just look at the table both virtual are negative..

Answer 88

maybe retrying witht he lessons I showed ? :/ (

Answer 89

where are the lessons ?

Answer 90

\(\color{#0cbb34}{\text{Originally Posted by}}\) @zarkam21

\(\color{#0cbb34}{\text{End of Quote}}\)

Answer 91

https://assets.questioncove.com/attachments/1526415774-5afb343e22389964ba5f6400-image.png

Answer 92

hold on

Answer 93

hmm I agreed to D after watching this video yesterday
https://www.khanacademy.org/science/physics/geometric-optics/lenses/v/thin-lens-equation-and-problem-solving
@8.25

Answer 94

Did you find the answer

Answer 95

maybe A

Answer 96

because that would be the opposite

Answer 97

no i won't pick A

Answer 98

Then?

Answer 99

https://prnt.sc/jicf38

Answer 100

http://www.physicsclassroom.com/class/refrn/Lesson-5/The-Mathematics-of-Lenses
from ^^

Answer 101

the negative indicates it is virtual

Answer 102

SO B

Answer 103

i'm still looking for more info maybe 5 minutes ?

Answer 104

yeah sure no prob take your time

Answer 105

http://www.khadley.com/courses/Physics/ph_212/topics/rayOptics/images/slide32.png?crc=493359552
yeah i'll go with B

Answer 106

if the image distance is negative the image will be virtual according to that ^^both can have virtual image