1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
sineoko [7]
3 years ago
10

This question relates to the practicality of searching for intelligent life in other solar systems by detecting their radio broa

dcasts (or aliens find us from ours). The closest stars are 4 light years away from us. How far away must you be from a 781 kHz radio station with power 50.0 kW for there to be only one photon per second per square meter? Assume that the photons spread out spherically. The area of a sphere is 4????????2.
Physics
1 answer:
Montano1993 [528]3 years ago
3 0

Answer:

2.77287\times 10^{15}\ m

Explanation:

P = Power = 50 kW

n = Number of photons per second

h = Planck's constant = 6.626\times 10^{-34}\ m^2kg/s

\nu = Frequency = 781 kHz

r = Distance at which the photon intensity is i = 1 photon/m²

Power is given by

P=nh\nu\\\Rightarrow n=\dfrac{P}{h\nu}\\\Rightarrow n=\dfrac{50000}{6.626\times 10^{-34}\times 781000}\\\Rightarrow n=9.66201\times 10^{31}\ photons/s

Photon intensity is given by

i=\dfrac{n}{4\pi r^2}\\\Rightarrow 1=\dfrac{9.66201\times 10^{31}}{4\pi r^2}\\\Rightarrow r=\sqrt{\dfrac{9.66201\times 10^{31}}{4\pi}}\\\Rightarrow r=2.77287\times 10^{15}\ m

The distance is 2.77287\times 10^{15}\ m

You might be interested in
Which of the following layers in the earth has the highest density?
Ray Of Light [21]
If we are being specific, the inner core has the highest density, but if not then the core in general
5 0
4 years ago
A 1000 kg elevator is accelerated upward at a rate of 0.70 m/s2. What is the tension in the cable pulling the elevator upward wh
Masteriza [31]

Answer:

Tension is also known as Force...

and Force is mass× acceleration.

so....1000×0.70=700N

5 0
3 years ago
Read 2 more answers
A "570-W" electric heater is designed to operate from 120-V lines. What current does it draw? If the line voltage drops to 110 V
Viefleur [7K]

Answer:

Watts=Volt*Amps

So A=570/120=4.75amps

If voltage drops to 110V We get A=570/110=5.(18...)amps

4 0
3 years ago
Read 2 more answers
A scaffold of mass 57 kg and length 6.5 m is supported in a horizontal position by a vertical cable at each end. A window washer
Mrac [35]

Explanation:

The given data is as follows.

     m_{1} = 57 kg,        m_{2} = 79 kg

      l_{1} = 6.5 m,         l_{2} = (6.5 - 1.9) m = 4.6 m

(a)  The sum of torque ends about far end is as follows.

    m_{1}g \frac{l_{1}}{2} + m_{2}g \times l_{2} - T \times l_{1} = 0

     57 \times 9.81 \times \frac{6.5}{2} + 79 \times 9.81 \times (6.5 - 1.9) - T \times 6.5 = 0

                     T = 828 N

Therefore, 828 N is the tension in the cable closer to the painter.

(b)  Now, we will calculate the sum about close ends as follows.

m_{1}g \frac{l_{1}}{2} + m_{2}g \times (1.9) - T \times l_{1}    

  57 \times 9.81 \times \frac{6.5}{2} + 79 \times 9.81 \times (1.9) - T \times 6.5 = 0

                            T= 506 N

Therefore, 506 N is the tension in the cable further from the painter.  

8 0
3 years ago
Two identical metal balls a and b are mounted on insulating rods. Ball a has a charge of +q/2 and ball b is initially uncharged.
oksano4ka [1.4K]

Answer:

Help me please?

Explanation:

Did you get the answer? I believe it’s either C. +q or D. 0

6 0
3 years ago
Read 2 more answers
Other questions:
  • Which structure is found in all EUKARYOTIC cells? Large central vacuole, Golgi apparatus, flagella, cilia
    7·1 answer
  • Most of uranus's atmosphere is composed of
    11·2 answers
  • A 40 cm. diameter sphere that weighs 400 n is released from rest underwater in claytor lake. its initial acceleration is about:
    11·1 answer
  • An ambulance with a siren emitting a whine at 1790 Hz overtakes and passes a cyclist pedaling a bike at 2.36 m/s. After being pa
    5·1 answer
  • Which statement best describes perigee?
    6·1 answer
  • An ideal air-filled parallel-plate capacitor has round plates and carries a fixed amount of equal but opposite charge on its pla
    15·1 answer
  • What does wave speed have to do with all SONAR AND RADAR technologies?
    12·2 answers
  • What is the Coriolis effect? Explain how<br> this works
    9·1 answer
  • 5.54 Two kilograms of air within a piston–cylinder assembly WP execute a Carnot power cycle with maximum and minimum temper atur
    10·1 answer
  • Look at the equation. What detail is missing? 3 m/s2= (33 m/s - X)/30 S <br>​
    7·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!