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Ede4ka [16]
3 years ago
12

PLEASE HELP! TRUE OR FALSE!

Physics
2 answers:
SpyIntel [72]3 years ago
8 0

Answer:

<h3>About the firs question.</h3>

The first statement is completely true. An image is attached. You can observe than a concave mirror like it's shown, the focal points is on the optic axis, and all rays converge in that point.

<h3>About the second question.</h3>

<em>A dispersive medium refers to mediums where waves of different frequencies travel at different velocities. </em>In addition, the relation between frequency and degree of refraction of the medium is that waves with lower frequency will bend less when passing through the dispersive medium. For example, if we pass a red light through a medium, and then we pass a violet light, we'll see the difference in the angle of refraction, the violet light will bend more than the red one.

Therefore, the answer to the second question is "<em>dispersive media waves of high frequency refract more than waves of low frequency do".</em>

<em />

<h3>About the third question.</h3>

The reason why Roemer's measurement of the speed of light was inaccurate is:<em> "He did not know the accurate diameter of the Earth's orbit".</em>

At that time, during 1668-1674, the diameter of Earth's orbit wasn't accurate, which added error of delay to his Roemer's measurement. However, he was the first scientist in deduct a finite speed of light, before him, it was known that the speed of light was infinite.

<h3>About the fourth question.</h3>

For convex lenses we have the relation between distances and highnesses:

\frac{d_{o} }{d_{i} }=\frac{h_{o}}{h_{i}}

We have:

f=10.0 \ cm

d=5.0 \ cm

h_{o}=3.0 \ cm

So, we can deduct that the object is d_{o}=15.0 \ cm away from the lens. But, we need to calculate the distance of the image d_{i} with this relation:

\frac{1}{f}=\frac{1}{d_{o} } +\frac{1}{d_{i} }

Replacing all values, we have:

\frac{1}{10}=\frac{1}{15}  +\frac{1}{d_{i}}\\\frac{1}{10}-\frac{1}{15} =\frac{1}{d_{i}}\\\frac{1}{d_{i}}=\frac{15-10}{150}=\frac{5}{150}\\d_{i}=\frac{150}{5}=30

Now, we can calculate the highness of the image:

\frac{d_{o} }{d_{i} }=\frac{h_{o}}{h_{i}}\\\frac{15}{30}=\frac{3}{h_{i}}\\h_{i}=\frac{3(30)}{15}=6

Therefore, the image height is 6 centimetres.

Fed [463]3 years ago
4 0
For the first true or false question, it is true.
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Kipish [7]

Answer:

Direct current is used in any electronic device with a battery for a power source. It is also used to charge batteries, so rechargeable devices like laptops and cell phones

Explanation:

8 0
3 years ago
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A battery-operated car utilizes a 12.0 V system. Initially, the car is at rest at the base of a 195 m high hill. Some time later
ale4655 [162]

Answer:

140265.8 C = 1.403 × 10⁵ C

Explanation:

The battery's electric potential energy is used to account for the kinetic and potential work done in moving the car up this hill.

Potential work required to move the 757 kg car up a vertical height of 195 m = mgh

P.E = 757 × 9.8 × 195 = 1446627 J

Kinetic work done = (1/2)(m)(v²)

K.E = (1/2)(757)(25²) = 236562.5 J

Total work done in moving the car up that height = 1446627 + 236562.5 = 1683189.5 J

And this would be equal to the potential of the battery.

For the battery, potential difference = (electric potential energy)/(charges moved)

ΔV = ΔU/q

q = ΔU/ΔV

ΔU = 1683189.5 J

ΔV = 12.0 V

q = 1683189.5/12 = 140265.8 C

7 0
3 years ago
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Please help!
Yanka [14]

Answer:

V=3.57 × 10^6 m/s

hope it is helpful..

7 0
3 years ago
An object 5.Ocm in the length is placed at a distance of 20cm in front of convex mirror
andrew-mc [135]

Answer:

Position = \frac{60}{7}\ cm behind the mirror

Nature = Virtual and Erect

Size = \frac{15}{7}\ cm : Diminished

Explanation:

Sign convention-Distance measured to the left of pole is negative and to the right of pole is positive.

Object distance = u = -20 cm

Focal length = f = Radius of curvature/2 = 30/2 = 15 cm

We have to use mirror formula to find image distance.

\frac{1}{u}+\frac{1}{v}=\frac{1}{f}\\ \frac{1}{-20}+\frac{1}{v}=\frac{1}{15}\\ \frac{1}{v}=\frac{7}{60}\\v=\frac{60}{7}\ cm

Since the image distance is positive, it is formed behind the mirror or a virtual image is formed.

Magnification = =\frac{h_{image}}{h_{object}}=-\frac{v}{u}=\frac{60}{7\times20}=\frac{3}{7}

Height of the object = 5 cm

Height of the image = 5\times\frac{3}{7}=\frac{15}{7}\ cm

Since the height of the image is positive and less than the size of object,it is erect and diminished.

4 0
3 years ago
An ambulance emits a frequency of 450 Hz from its siren. What frequency is heard by a man as the ambulance moves toward him? les
Zepler [3.9K]

Frequency is defined as the number of repetitions of waves occurring in 1 second. The frequency heard by the man as the ambulance move toward him will be greater than 450 Hz.

<h3>What is the frequency ?</h3>

Frequency is defined as the number of cycles completed in 1 second. Frequency is given by the formula as,

\rm{Frequency =\frac{1}{time } }

As the formula shows frequency is inversely proportional to the time that shows if the time is decreasing frequency will increase and vice versa.

In the above case, the ambulance is moving toward the men. So that the time to meet up is decreased that's why the frequency will be greater than the initial frequency from the siren.

Hence the frequency heard by the man as the ambulance move toward him will be greater than 450 Hz.

To learn more about  frequency refer to the link ;

brainly.com/question/4393505

3 0
3 years ago
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