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3 years ago

Which of the following means that an image is located behind a lens? A. +di B. -di C. -do D. +do

1 answer:

4 0

For a lens, the following sign convention is generally used:

- f (the focal length) is positive for a converging lens and negative for a diverging lens
- $d_o$ (the distance of the object from the lens) is positive if the object is in front of the lens and negative if it is behind the lens
- $d_i$ (distance of the image from the lens) is positive if the image is behind the lens (real image) and negative if the image is in front of the lens (virtual image)

Therefore, the correct option is
A. +di
which mens that the image is real and located behind the lens.

You might be interested in

Which of the following is a false statement? Select one:

Art [367]

Answer:

The false statement is in option 'd': The center of mass of an object must lie within the object.

Explanation:

Center of mass is a theoretical point in a system of particles where the whole mass of the system is assumed to be concentrated.

Mathematically the position vector of center of mass is defined as

$\overrightarrow{r}_{com}=\int \overrightarrow{r}_{i}dm$

where,

$\overrightarrow{r}_{i}$ is the position vector of the mass dm.

As we can see for homogenous symmetrical objects such as a sphere,cube,disc the center of mass is located at the centroid of the shapes itself but in many shapes it is located outside the body also.

Examples of shapes in which center of mass is located outside the body:

1) Horseshoe shaped body.

2) A thin ring.

In many cases we can make shapes of bodies whose center of mass lies outside the body.

6 0

3 years ago

We now have an algebraic expression with only one variable, which can be solved. Once we have that, we can plug it back into one

Len [333]

Answer:

A=1

B=-2

Explanation:

Part A and B of the question wasn't given, however, I attached the relevant parts to solve this question as follows.

From part B as attached, it shows that the right option is C which is

2A+3B=-4

Substituting B with 3A-5 then we form the second equation as shown

2A+3(3A-5)=-4

By simplifying the above equation, we obtain

2A+9A-15=-4

Re-arranging, then

11A=-4+15

Finally

11A=11

A=1

To obtain B, we already know that 3A-5 so substituting the value of A into the above then we obtain

B=3(1)-5=-2

Therefore, required values are 1 and -2

3 0

4 years ago

lanet R47A is a spherical planet where the gravitational acceleration on the surface is 3.45 m/s2. A satellite orbitsPlanet R47A

qaws [65]

$2.6×10^6\:\text{m}$

Explanation:

The acceleration due to gravity g is defined as

$g = G\dfrac{M}{R^2}$

and solving for R, we find that

$R = \sqrt{\dfrac{GM}{g}}\:\:\:\:\:\:\:(1)$

We need the mass M of the planet first and we can do that by noting that the centripetal acceleration $F_c$ experienced by the satellite is equal to the gravitational force $F_G$ or

$F_c = F_G \Rightarrow m\dfrac{v^2}{r} = G\dfrac{mM}{r^2}\:\:\:\:\:(2)$

The orbital velocity v is the velocity of the satellite around the planet defined as

$v = \dfrac{2\pi r}{T}$

where r is the radius of the satellite's orbit in meters and T is the period or the time it takes for the satellite to circle the planet in seconds. We can then rewrite Eqn(2) as

$\dfrac{4\pi^2 r}{T^2} = G\dfrac{M}{r^2}$

Solving for M, we get

$M = \dfrac{4\pi^2 r^3}{GT^2}$

Putting this expression back into Eqn(1), we get

$R = \sqrt{\dfrac{G}{g}\left(\dfrac{4\pi^2 r^3}{GT^2}\right)}$

$\:\:\:\:=\dfrac{2\pi}{T}\sqrt{\dfrac{r^3}{g}}$

$\:\:\:\:=\dfrac{2\pi}{(1.44×10^4\:\text{s})}\sqrt{\dfrac{(5×10^6\:\text{m})^3}{(3.45\:\text{m/s}^2)}}$

$\:\:\:\:= 2.6×10^6\:\text{m}$

5 0

3 years ago

A student environmental group is creating a campaign for locally sourced energy resources.What would be best for them to feature

Ivenika [448]

Answer:

A farmer with a field of solar panels.

Explanation:

The closest to a locally sources energy would have been

A coal mine located in their county.

But coal as an energy source is not environmentally friendly due to carbon emission, and should not be what the group should advocate for.

The best bet for them is

A farmer with a field of solar panels.

As solar panels are a source of green energy and green energy is what the environmental group should often and always advocate for

3 0

3 years ago

When a boat moves through the water, the waves in front of the boat bunch up, while the waves behind the boat spread out. this i

liberstina [14]

Answer: Doppler Effect

Doppler Effect can be described as the change in wavelength of a wave like upward shift in frequency for an object whom is approaching and an apparent downward shift in frequency for observers from whom the source is receding. This effect can be observed when a boat moves through the water then the waves in front bunch up while the waves behind the boat spread out.

8 0

3 years ago