Object image height and distance relationship | Geometric optics | Physics | Khan Academy
A1 A2 B1 B2 C1 C2
another
US / əˈnʌðə(r) /
•UK / əˈnʌðɚ /
- adjecitve
- One more, but not this
- determiner
- One more added
- pronoun
- One more (thing)
from
US / frəm /
•UK / frʌm, frɑm,frəm /
- preposition
- Starting at a particular place, time or level
hopefully
US / ˈhəʊpfəli /
•UK / ˈhopfəli /
- adverb
- In a manner wishing something to happen
base
US / beɪs /
•UK / bes /
- noun
- Place military personnel live, train, and operate
- Bottom part of an object that touches a surface
- Unit of counting, e.g. 10 for counting
- Most important idea or ingredient to add others
- Origin or start from which something came
- Main place where an organization or a person works
- verb
- To use as the starting point or origin for
- To have as the main location for (company, etc.)
call
US / kɔ:l /
•UK / kɔl /
- noun
- A order or request for action
- The sound an animal makes, often when in danger
- A correct prediction, e.g. a decision in a game
- A short visit to a place or person
- A decision by a referee or umpire in a game
- verb
- To make a request or order for action
- (Animal) to make sounds to warn of danger
- To announce the date of an election
- To make a judgment about something
- To give someone or something a name
- To guess in advance the result or outcome
- To visit a place or person for a short time
- To phone someone
- To speak, announce or shout in a loud voice
two
US / tu: /
•UK / tu /
- number
- 2
and
US / ənd /
•UK / ənd, ən,ænd /
- conjunction
- Used to refer to two or more things
- Plus; in addition; on top of that
- Used to introduce an action that follows another
height
US / haɪt /
•UK / haɪt /
- noun
- Distance of something from the bottom to the top
come
US / kʌm /
•UK / kʌm /
- verb
- To arrive at a place
- (Of mail) to be delivered
- To move toward someone; go with someone
- To reach a certain point or state
distance
US / 'dɪstəns /
•UK / ˈdɪstəns /
- noun
- Lack of friendliness toward another person
- Amount of space between two places or things
- verb
- To make it clear that you are not involved
over
US / 'əʊvə(r) /
•UK / ˈovɚ /
- adverb
- Finished; no longer happening
- Towards the ground/away from a standing position
- noun
- A set of six consecutive balls bowled in cricket
- other
- Finished
- preposition
- Showing the relation when a thing is above another
- On or covering something
- Above or across something
- More than you need
- From one side to the other
- In the direction of; toward
out
US / aʊt /
•UK / aʊt /
- adverb
- No longer stylish (e.g. fashion)
- Away from home, business, or the usual place
- In a direction/movement away from inside or center
- noun
- Act when a batter cannot continue playing
- verb
- To tell people a secret
start
US / stɑ:t /
•UK / stɑrt /
- noun
- First time or place that a thing exists; beginning
- First opportunity to achieve something, e.g. a job
- Sudden action or movement because you are scared
- other
- Beginning of something in place or time
- verb
- To do, be or happen for the first time; begin
- To turn something on
since
US / sɪns /
•UK / sɪns /
- adverb
- At a point before the present time
- conjunction
- For this reason; because
- preposition
- From the time in the past that
set
US / set /
•UK / sɛt /
- adjecitve
- Prepared for something; ready
- noun
- Complete group of something
- Place where a television show or movie is filmed
- Group of games in a tennis match
- Device that receives radio or television signals
- verb
- To make a clock state or ring at a particular time
- To decide upon or choose something
- To make something ready for use (e.g. table)
- To decide on a price for something
- To become hard (of glue, concrete etc.)
- To be located in a specific place or time
- To put (e.g. a vase) down carefully in a place
- To put someone in a certain condition or state
- (Of the sun) to go lower than the horizon
those
US / ðəʊz /
•UK / ðoz /
- determiner
- The people or things we are talking about
- pronoun
- The objects far from the speaker
object
US / 'ɒbdʒɪkt /
•UK / ˈɑbdʒɪkt /
- noun
- Something you can see or touch, but is not alive
- Goal or purpose of a particular plan or activity
- The thing that the action of a verb acts upon
- verb
- To disagree; to protest against an idea or plan
well
US / wel /
•UK / wɛl /
- adjecitve
- Being in a fortunate, good condition or state
- Healthy and in good condition
- adverb
- In an acceptable, proper, or successful manner
- In a complete, total, or full manner
- A great and considerable degree
- In a successful way, in a good or satisfactory way
- exclamation
- Used to begin or continue a particular statement
- Used to show you want to start saying something
- Used to express that you are waiting for a reply
- You say this to change the topic of a conversation
- Used to indicate you are making a final remark
- noun
- Long deep hole in the ground to get water
- verb
- To cause your eyes to fill with tears
just
US / dʒʌst /
•UK / dʒʌst /
- adjecitve
- Proper or appropriate; as is deserved
- Doing or being what is right or fair
- Legally correct; having enough evidence
- adverb
- Almost; nearly
- Exactly at the time of
- Exactly (the same as, like)
anyway
US / ˈeniweɪ /
•UK / ˈɛniˌwe /
- adverb
- A word used to change the topic of a conversation
this
US / ðɪs /
•UK / ðɪs /
- adjecitve
- Used to indicate something already been discussed
- Used to indicate something happening around now
- adverb
- An indication by a physical motion or gesture
- A specific amount of
- determiner
- Person, thing, or idea near you
- pronoun
- Person, thing that has already been discussed
let
US / let /
•UK / lɛt /
- verb
- To allow someone to do something
- Introducing a suggestion to do something together
- To rent a house, etc. to others
one
US / wʌn /
•UK / wʌn /
- pronoun
- You; we; people in general; someone
- The thing or person previously referred to
- adjecitve
- Used to refer to people generally
- Being a strong example of (something mentioned)
- number
- Number 1
you
US / jʊ /
•UK / ju /
- pronoun
- Person someone is speaking or writing to
- Person or people in general
little
US / 'lɪtl /
•UK / ˈlɪtl /
- adjecitve
- Being short in length of time
- Not great in size, amount, or degree; small
- Being very young or younger than others
- adverb
- By an amount or degree that is not very much
- Not often; rarely
- noun
- A person's name
might
US / maɪt /
•UK / maɪt /
- other
- Used to politely request an action
- Used to express that something could happen
- Power, strength, force or influence
other
US / 'ʌðə(r) /
•UK / ˈʌðər /
- adjecitve
- A thing different from that mentioned
- determiner
- (Something) else; not the first (one)
- pronoun
- Being the one and only thing of that category
the
US / ðə /
•UK / ðə /
- article
- Used to refer to something already mentioned
- Used to show there is only one of something
- determiner
- Used to describe all of a family
fruit
US / fru:t /
•UK / frut /
- noun
- Result or product of something
- Food that grows on a tree or bush, usually sweet
- verb
- To grow e.g. apples, bananas, as a plant or a tree
also
US / 'ɔ:lsəʊ /
•UK / ˈɔlso /
- adverb
- In addition; too; in a similar way
opposite
US / ˈɔpəzit /
•UK / ˈɑpəzɪt /
- adjecitve
- Being totally different from
- noun
- Person, thing that is totally different to another
- preposition
- Across from or on the side facing something
image
US / 'ɪmɪdʒ /
•UK / ˈɪmɪdʒ /
- noun
- Picture, sculpture or painting of something
- General idea or opinion of something
- verb
- To obtain pictures by scanning them with a machine
last
US / lɑ:st /
•UK / læst /
- adjecitve
- Most recent; the latest
- The one before
- adverb
- Final; with nothing following; after all others
- Most recent; the latest
- determiner
- The one at the end
- verb
- To remain or continue for a certain period of time
ratio
US / ˈreɪʃiəʊ /
•UK / ˈreɪʃioʊ /
- noun
- The relationship in relative size, etc.
have
US / həv /
•UK / hæv /
- verb
- To drink, smoke, eat or use something
- To experience the effects of something
- To organize an event, or join in an activity
- To own, possess, or hold something
- To cause to happen or produce a particular effect
extra
US / 'ekstrə /
•UK / 'ekstrə /
- adjecitve
- More than necessary; additional
- noun
- Items more than you need; additional items
- Person who has a small part in a movie
- Special version of a newspaper
with
US / wɪð /
•UK / wɪð, wɪθ /
- preposition
- As an employee of a certain company
- Against something or someone
- By using something as a means
- Due to; because of
- Including
- Possessing as a feature
- Related to
- (Of the manner/attitude by which you do something)
- Used to express that people or things are together
know
US / nəʊ /
•UK / noʊ /
- verb
- To be familiar with a person or place, thing
- To feel sure or be convinced about something
- To discover or be aware of something
- To be able to distinguish
- To have knowledge of things
could
US / kəd /
•UK / kʊd /
- other
- Past form of 'can' to mean have ability
- Used to ask for something politely, or to offer
similar
US / ˈsɪmələ(r) /
•UK / ˈsɪməlɚ /
- adjecitve
- Nearly the same; alike
first
US / fɜ:st /
•UK / fɚst /
- adjecitve
- 1st; Coming before all others in time or place
- noun
- Something that has not happened before
- Position of the winner of a competition
triangle
US / ˈtraɪæŋgl /
•UK / ˈtraɪˌæŋɡəl /
- noun
- Three people connected with each in a relationship
- A three-sided piece of metal used in orchestras
- A closed shape with three straight sides
down
US / daʊn /
•UK / daʊn /
- adjecitve
- Being sad, sick, or unhappy
- Not operating, working, or functioning as expected
- adverb
- In a sitting or lying position
- Towards or on the ground, floor, or bottom
- Written or copied onto a piece of paper or book
- noun
- A period of play in American Football
- The soft, smooth hairs that cover a bird's body
- preposition
- Along something's path, course, or direction
- Going from a higher position to a lower position
- verb
- To eat or drink very quickly and without stopping
each
US / i:tʃ /
•UK / itʃ /
- determiner
- Every one of two or more things
- pronoun
- Per one person or thing
what
US / wɒt /
•UK / hwɑt, hwʌt, wɔt, wʌt,hwət, wət /
- pronoun
- Thing or things that; the same kind as
- Used to emphasize something you are about to say
- adjecitve
- Used to refer to a particular amount, or number
- Used to place emphasis on a particular quality
- adverb
- To a certain degree
- determiner
- Question words used for asking for information
- exclamation
- Used to express excitement, shock, or surprise
- Used to ask people to repeat something they said
that
US / ðæt /
•UK / ðæt, ðət /
- adjecitve
- The person or thing being talked about
- Used to identify something both the speakers know
- adverb
- Used to reinforce adjectives and adverbs
- To such a degree
- conjunction
- Used to connect a noun clause
- Used to introduce an adverbial clause
- Used to introduce a noun clause
- determiner
- Used as a noun to refer to something
- pronoun
- Referring an object far away
- Used to refer to the relative pronoun ‘which’
bunch
US / bʌntʃ /
•UK / bʌntʃ /
- noun
- A group of things of the same kind
- verb
- To group people or things closely together
- (Cloth) to gather/be gathered together in folds
find
US / faɪnd /
•UK / faɪnd /
- noun
- Object discovered by chance
- Things that have been discovered from searching
- verb
- To become aware of something that is happening
- To discover or meet by chance
- To decide if someone is guilty of a crime, or not
- To learn through study, research, or effort
- To discover something by looking for it
right
US / raɪt /
•UK / raɪt /
- adjecitve
- Correct or true
- The south side of you looking at the rising sun
- adverb
- Exactly in a place or time
- Being appropriate for a particular event
- In a straight or direct manner
- noun
- Something you are legally or morally allowed to do
- Ideal of what is just and good
- Political view based on conservatism
- verb
- To fix something previously wrong or unjust
- To make upright, as a boat that has turned over
length
US / leŋθ /
•UK / leŋθ /
- noun
- Distance from one end of a pool to the other
- Measurement of distance or of time
show
US / ʃəʊ /
•UK / ʃo /
- noun
- False display of love, emotion or action
- An event for displaying or promoting goods
- Play, opera or theater production
- Presentation that is broadcast on TV or radio
- verb
- To be easily seen or displayed
- To display your emotions or feelings
- To let someone see something; display
- To explain or teach how something is done
- To lead someone somewhere; point them to something
- To prove something to be true, correct
- To reveal or allow something to be seen
their
US / ðɛː /
•UK / ðer /
- determiner
- Belonging to them
figure
US / ˈfiɡə /
•UK / ˈfɪɡjɚ /
- noun
- Your body shape
- Numbers in a calculation
- Doll-like thing meant to represent a person
- Picture or diagram giving information in a text
- Person who is very important or famous
- Shape of a person seen indistinctly or in outline
- Amount that is expressed in numbers
- verb
- To appear in a game, play or event
- To calculate how much something will cost
- To understand after thinking; work out
lens
US / lenz /
•UK / lɛnz /
- noun
- Structure in the eye or camera that focuses light
- other
- Pieces of glass or plastics to improve vision
between
US / bɪˈtwi:n /
•UK / bɪˈtwin /
- preposition
- From one person, thing, or place, to another
- In the space that separates two objects
- Among two or more people who share something
mechanic
US / məˈkænɪk /
•UK / mɪˈkænɪk /
- noun
- A person who looks after/works with machinery
everything
US / 'evrɪθɪŋ /
•UK / ˈɛvriˌθɪŋ /
- pronoun
- All of the things mentioned
way
US / weɪ /
•UK / we /
- adverb
- Used to emphasize the amount of something
- noun
- Particular aspect of something being thought about
- One of various choices that could be made
- Particular existing condition or state
- (Often long) distance or length of time
- How something is done
- Route to go to a place
- Small street
- Usual behavior, emotions or habits of someone
all
US / ɔ:l /
•UK / ɔl /
- adverb
- Completely; totally
- determiner
- Being every one of something
- pronoun
- 100% of something; the complete amount
both
US / bəuθ /
•UK / boθ /
- determiner
- Used to refer to two things at the same time
- pronoun
- Used to refer to two things at the same time
useful
US / ˈju:sfl /
•UK / ˈjusfəl /
- adjecitve
- That can help with a particular task
rewrite
US / ˌri:'raɪt /
•UK / riˈraɪt /
- verb
- To write again to improve, or correct errors
angle
US / ˈæŋgl /
•UK / ˈæŋɡəl /
- noun
- Place where two lines or surfaces meet
now
US / naʊ /
•UK / naʊ /
- adverb
- At the present time or moment
- Right away or in the next possible moment
- Used to refer to something that just happened
- Time between the present and a moment in the past
- conjunction
- Resulting from or because of something
really
US / ˈri:əli /
•UK / ˈriəˌli, ˈrili /
- adverb
- Used to stress something that is said; definitely
- In a true or accurate manner
- Very
same
US / seɪm /
•UK / sem /
- adjecitve
- Being equal in quality and amount
- Identical; not different
- Not changing; constant
maybe
US / ˈmeɪbi /
•UK / ˈmebi /
- adverb
- Possibly but not certainly; perhaps
convex
US / ˈkɒnveks /
•UK / ˈkɑ:nveks /
- adjecitve
- Having a surface that curves outward like a ball
yellow
US / ˈjeləʊ /
•UK / ˈjeloʊ /
- adjecitve
- Color of lemons or the sun
- Lacking in courage; cowardly (used as an INSULT)
- verb
- To turn yellow, often due to being old
video
US / 'vɪdɪəʊ /
•UK / ˈvɪdiˌo /
- adjecitve
- Of a moving film, with sound
- noun
- Recording capturing action with sound
- verb
- To make a moving film of, with sound
size
US / saɪz /
•UK / saɪz /
- noun
- How big or small a thing is
- Standard measurements for clothing, shoes
- verb
- To make something to fit a particular measurement
- To organize or group from small to large
want
US / wɔnt /
•UK / wɑnt, wɔnt /
- noun
- Something you desire or wish for
- State or condition of poverty
- verb
- To desire or wish for something; hope for a thing
relationship
US / rɪˈleɪʃnʃɪp /
•UK / rɪˈleʃənˌʃɪp /
- noun
- Connection between two or more people or things
- Way people interact or live with each other
- Romantic or loving friendship between two people
here
US / hɪə(r) /
•UK / hɪr /
- adverb
- In this place; at this location, position or time
already
US / ɔ:lˈredi /
•UK / ɔlˈrɛdi /
- adverb
- Having happened or been done before this time
realize
US / 'ri:əlaɪz /
•UK / ˈriəˌlaɪz /
- verb
- To become aware of or understand mentally
write
US / raɪt /
•UK / raɪt /
- verb
- To compose letters and words on paper or a screen
- To invent or create a computer program
- To create a song or piece of music
side
US / saɪd /
•UK / saɪd /
- adjecitve
- In addition to the central or most important thing
- Next to, or very close to, the right or left of
- noun
- Position or opinion that is opposite to another
- Right or left part of a person's body
- Feature of someone's personality
- Straight edge of an object
- One of two or more groups fighting each other
- verb
- To decide to agree with one point, not the other
will
US / wɪl /
•UK / wɪl /
- noun
- Desire or choice of someone
- Document saying who gets your money when you die
- Strong desire to do something; determination
- Desire to do something; strong wish to do
- other
- Used with verbs to express the future
- verb
- To leave property to someone after your death
- To use mental effort to make something happen
- Am (is, are) likely to do
- To influence someone to do something
- To make something happen by strongly wanting it
geometry
US / dʒiˈɒmətri /
•UK / dʒiˈɑ:mətri /
- noun
- Mathematical study of shapes, surfaces, and space
- Mathematical shape of something
focal
US / 'fəʊkl /
•UK / ˈfokəl /
- adjecitve
- (Of a point) being the main or important one