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siniylev [52]
3 years ago
6

Why do reflecting telescopes usually have a secondary mirror in addition to a primary mirror?

Physics
1 answer:
Gemiola [76]3 years ago
8 0
Once the starlight or moonlight comes down the tube and hits the big main mirror at the bottom, it's reflected, and heads back up the tube, along the same way it came in. But if you're looking through an eyepiece, the eyepiece is on the SIDE of the tube. So you need another small mirror, to catch the focused light before it goes up out of the tube, and send it sideways to the eyepiece.
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What is the period of a soundwave whose wavelength is 20.0 m? Use values from the book and show ALL of your work.
Liono4ka [1.6K]
<h3><u>Answer;</u></h3>

Period = 1/17 seconds

<h3><u>Explanation;</u></h3>
  • Wavelength is related to period by the expression:

<em>speed = wavelength / period </em>

  • If we are given the speed, then we can easily calculate the period at the wavelength of 20 m.

<em>Given the speed of sound wave as 340 m/s </em>

<em>Period = Wavelength/ speed</em>

<em>            = 20 m/340 m/s</em>

<em>            </em><u><em>= 1/17 seconds</em></u>

7 0
3 years ago
Which pair of graphs represent the same motion?
GaryK [48]
Show me the graphs and i would be glad to help u
7 0
3 years ago
Please help!! (Picture attached)
KonstantinChe [14]
Well it is definitely answer B because when light is on for a long time it heats up a lot.the thermometer obviously went up which means the light bulb had more energy and was hotter than the start of it
3 0
4 years ago
What quantity is the rate of change of velocity? Displacement Acceleration Final velocity
MariettaO [177]

Answer:

Acceleration

Explanation:

The quantity of the rate of change of velocity is termed the acceleration of the body.

Acceleration is the rate of change of velocity with time;

  A  = \frac{v - u}{t}  

A is the acceleration

v is the final velocity

u is the initial velocity

t is the time taken

 

7 0
3 years ago
What is the peak emf generated by a 0.250 m radius, 500-turn coil is rotated one-fourth of a revolution in 4.17 ms, originally h
zysi [14]

Complete question:

What is the peak emf generated by a 0.250 m radius, 500-turn coil is rotated one-fourth of a revolution in 4.17 ms, originally having its plane perpendicular to a uniform magnetic field 0.425 T. (This is 60 rev/s.)

Answer:

The peak emf generated by the coil is 15.721 kV

Explanation:

Given;

Radius of coil, r = 0.250 m

Number of turns, N = 500-turn

time of revolution, t = 4.17 ms = 4.17 x 10⁻³ s

magnetic field strength, B = 0.425 T

Induced peak emf = NABω

where;

A is the area of the coil

A = πr²

ω is angular velocity

ω = π/2t = (π) /(2 x 4.17 x 10⁻³) = 376.738 rad/s =  60 rev/s

Induced peak emf = NABω

                               = 500 x (π x 0.25²) x 0.425 x 376.738

                               = 15721.16 V

                               = 15.721 kV

Therefore, the peak emf generated by the coil is 15.721 kV

5 0
3 years ago
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