I am correcting a test but need the formulas

[Psychospacecow]

I have a retest on Monday for a test I received a 33 on, but there are not formulas on the test I am correcting. I am going to post the questions I am currently unsure of and input would be greatly appreciated. I have corrected 10 multiple choice questions but the math itself I am issues with.

If you can provide the formula, that'll be plenty.

So, it begins.

13. A microwave oven warms food using electromagnetic waves with a frequency of 8.5x10^9 Hz. What is the wavelength of these microwaves in nm?

14. Light from a distant planet reaches Earth in 6.5 years. How far from Earth is this planet in meters?

15. A concave shaving mirror has a center of curvature of 12.0 cm. A man is shaving 5 cm in front of the mirror. What is the magnification of his face, as seen in the mirror?

16. What is the frequency of light from Mr. Teacher's laser pointer if it produces a coherent beam of 552 nm light?

17. A convex mirror has a focal length of 25.0 cm. At what distance from the mirror does the image of a person 1.0 m in front of the mirror appear?

A car is placed in front of a plane mirror at a distance of 3.5 meter. The car is 250 cm tall.
18. At what distance from the mirror does the image of the car appear? Include signs if necessary.

20. How tall does the car's image appear? Include signs if necessary.


An object is 3.0 cm in front of a convex mirror. The mirror has a radius of curvature of 6.0 cm. If the object has a height of 3.0 cm. find the following:
21. How tall is the image?

22. What is the magnification of the image?

Using a ray diagram, solve the problem above. Check your numbers with your calculations. (I'm probably just going to look this one up because I have no idea)

An object is 1.5 cm. tall is standing 5.0 cm. from a concave mirror that has a focal length of 3.0 cm.

23. How tall is the image?

24. What is the magnification of the image?

Using a ray diagram, solve the problem above. Check your numbers with your calculations.


I really appreciate any input. I don't need them solved. I need to be able to do that. We are provided a slip with the formulas during the test but that stays in class for the next group, so I don't have the formulas, and this was about 2 weeks ago.

I will be fine even if I fail as I did pass that 6 weeks with a 72, but if I can augment that a bit, I will.

[Petie]

13. A microwave oven warms food using electromagnetic waves with a frequency of 8.5x10^9 Hz. What is the wavelength of these microwaves in nm?

14. Light from a distant planet reaches Earth in 6.5 years. How far from Earth is this planet in meters?

16. What is the frequency of light from Mr. Teacher's laser pointer if it produces a coherent beam of 552 nm light?

I can't remember the mirror stuff at the moment but I can help with these three.

13 and 16 both use the frequency = wavelength / speed of light - just plug in and solve.
14 uses distance = time * speed of light but make sure you balance your units. 6.5 years won't directly match up against the unit for the speed of light.

A standard estimate of the speed of light is 300,000,000 m/s which should suffice unless you're supposed to use a more specific value.

[SERIOUSLY THOUGH*]

14. Light from a distant planet reaches Earth in 6.5 years. How far from Earth is this planet in meters?

Are we assuming that the planet and Earth don't move ? Because things are about to get mathematically insane if we factor in rotation around the planets' respective stars.

EDIT - If not, what Petie said.

[Petie]

Are we assuming that the planet and Earth don't move ? Because things are about to get mathematically insane if we factor in rotation around the planets' respective stars.

EDIT - If not, what Petie said.

Slight variations in distance based on the position of the planets in question would have a negligible impact on the calculation given the vast distance between them to begin with. Plus, there's not enough information given to factor it in even if you wanted to - we don't know the radius of the orbit or where each planet starts on their orbits to determine how much more/less the light would need to travel.

[Psychospacecow]

I do not know why but I am having an incredibly difficult time focusing.

13 is 3.5x10^7
14 is 6.15x10^16
15 is -.2
16 is 5.4x10^14

[Psychospacecow]

17 is -1.5m
Currently don't know how to do 18.

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figured out 18 and 20.

18 is 3.5 m.
20 is 2.5 m.