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3 years ago

Which statement correctly describes microscopes?

Physics

1 answer:

Ilya [14]3 years ago

4 0

Answer:

Hope you like it

Explanation:

Microscopes make small things appear larger. C: Hans and Zacharias Janssen created the first microscope. and D: A lens is a transparent material that helps show the details of things observed.

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How does the numerical value of "e" change as the shape of the ellipse approaches a straight line?

Aleks04 [339]

At eccentricity = 0 we get a circle For 0 < eccentricity < 1 we get an ellipse for eccentricity = 1 we get a parabola for eccentricity > 1 we get a hyperbola for infinite eccentricity we get a lineSHOW FULL ANSWER

4 0

3 years ago

A flock of ducks is trying to migrate south for the winter, but they keep being blown off course by a wind blowing from the west

Minchanka [31]

The ducks' flight path as observed by someone standing on the ground is the sum of the wind velocity and the ducks' velocity relative to the wind:

ducks (relative to wind) + wind (relative to Earth) = ducks (relative to Earth)

or equivalently,

$\vec v_{D/W}+\vec v_{W/E}=\vec v_{D/E}$

(see the attached graphic)

We have

ducks (relative to wind) = 7.0 m/s in some direction θ relative to the positive horizontal direction, or

$\vec v_{D/W}=\left(7.0\dfrac{\rm m}{\rm s}\right)(\cos\theta\,\vec\imath+\sin\theta\,\vec\jmath)$

wind (relative to Earth) = 5.0 m/s due East, or

$\vec v_{W/E}=\left(5.0\dfrac{\rm m}{\rm s}\right)(\cos0^\circ\,\vec\imath+\sin0^\circ\,\vec\jmath)$

ducks (relative to earth) = some speed v due South, or

$\vec v_{D/E}=v(\cos270^\circ\,\vec\imath+\sin270^\circ\,\vec\jmath)$

Then by setting components equal, we have

$\left(7.0\dfrac{\rm m}{\rm s}\right)\cos\theta+5.0\dfrac{\rm m}{\rm s}=0$

$\left(7.0\dfrac{\rm m}{\rm s}\right)\sin\theta=-v$

We only care about the direction for this question, which we get from the first equation:

$\left(7.0\dfrac{\rm m}{\rm s}\right)\cos\theta=-5.0\dfrac{\rm m}{\rm s}$

$\cos\theta=-\dfrac57$

$\theta=\cos^{-1}\left(-\dfrac57\right)\text{ OR }\theta=360^\circ-\cos^{-1}\left(-\dfrac57\right)$

or approximately 136º or 224º.

Only one of these directions must be correct. Choosing between them is a matter of picking the one that satisfies both equations. We want

$\left(7.0\dfrac{\rm m}{\rm s}\right)\sin\theta=-v$

which means θ must be between 180º and 360º (since angles in this range have negative sine).

So the ducks must fly (relative to the air) in a direction 224º relative to the positive horizontal direction, or about 44º South of West.

8 0

3 years ago

An electron in a hydrogen atom undergoes a transition from the n = 3 level to the n = 6 level. To accomplish this, energy, in th

Harlamova29_29 [7]

Answer: $1.816\times 10^{-19} J$

Explanation:

Given

$E=\frac{hc}{\lambda }$

$E=2.18\times 10^{-18}(\frac{1}{n_1^2}-\frac{1}{n_2^2})$

where h=Planck constant

c=speed of light

$E=2.18\times 10^{-18}(\frac{1}{3^2}-\frac{1}{6^2})$

$E=2.18\times 10^{-18}\times \frac{1}{12}$

$E=1.816\times 10^{-19} J$

7 0

3 years ago

Look at the Sankey diagram for a filament light bulb below. If the bulb is used in a desk lamp, what is the efficiency of the bu

guapka [62]

Answer:

The question does not state how the answer is to be entered. I would use 10% because that is most common.

Explanation:

You are using 300 J of energy to get 30 J of light energy. The fact that you can account for the left over energy is not relevant.

Efficiency = Work Out / Work In

Efficiency = 30 J / 300 J = 0.1

If you need this as a %, you can multiply by 100

Efficiency = 0.1 * 100 = 10%

6 0

3 years ago

What wave phenomena best describes the reason for the dark and light bands that

pickupchik [31]

Answer:

Interference

Explanation:

Interference is the phenomenon in which two waves superimpose to form a wave with smaller, larger or same amplitude.

There are two types of interference namely, constructive interference and destructive interference.

Constructive interference occurs when the waves are in phase and destructive interference occurs when the waves are out of phase.

In a double slit experiment, the two slits acts as sources of light and thus the waves combine to produce interference patterns. When the waves are in phase, that is the angle between them is 0°, they form a constructive interference pattern which gives rise to a light band. When the waves are out of phase, that is the angle between them is 180°, they form a destructive interference pattern which gives rise to a dark band.

Note also that diffraction patterns are also observed for wide slits but can be neglected for smaller slits.

4 0

3 years ago