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3 years ago

Why are red stars cooler than blue stars?

2 answers:

8 0

The hotter something is, the greater the frequency of radiation it emits.But since blue light is higher frequency than red light,that means that things that glow red are cooler then things that glow blue.

asambeis [7]3 years ago

6 0

OK both stars are burning and as they burn they emit electromagnetic radiation (light) and as we move in the light spectrum red comes before blue, so the star that looks red is cooler because as the temperature decreases the colour decreases

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A Ground Fault Circuit Interrupter (GFCI) works by comparing the amount of current going to and returning from equipment along t

DanielleElmas [232]

Choice-B is the correct one.

5 0

3 years ago

Read 2 more answers

A fan at a rock concert is 50.0 m from the stage, and at this point the sound intensity level is 114 dB. Sound is detected when

Marianna [84]

Answer:

A) $P=13.92\ J.s^{-1}$

B) $v=3730.9912\ m.s^{-1}$

C) $v=74.44\ mm.s^{-1}$

D) mosquitoes speed in part B is very much larger than that of part C.

Explanation:

Given:

Distance form the sound source, $s=50\ m$

sound intensity level at the given location, $\beta=114\ dB$

diameter of the eardrum membrane in humans, $d=8.4 \times 10^{-3}\ m$

We have the minimum detectable intensity to the human ears, $I_0=10^{-12}\ W.m^{-2}$

(A)

Now the intensity of the sound at the given location is related mathematically as:

$\beta=10\ log(\frac{I}{I_0} )$ ..........................................(1)

$114=10\ log\ (\frac{I}{10^{-12}} )$

$11.4=log\ I+12\ log\ 10$

$I=0.2512\ W.m^{-2}$

As we know :

$I=\frac{P}{A}$

$0.2512=\frac{P}{\pi\times \frac{8.4^2}{4} }$

$P=13.92\ J.s^{-1}$ is the energy transferred to the eardrums per second.

(B)

mass of mosquito, $m=2\times 10^{-6}\ kg$

Now the velocity of mosquito for the same kinetic energy:

$KE=\frac{1}{2} m.v^2$

$13.92=\frac{1}{2}\times 2\times 10^{-6}\times v^2$

$v=3730.9912\ m.s^{-1}$

(C)

Given:

Sound intensity, $\beta = 20\ dB$

Using eq. (1)

$20=10\ log\ (\frac{I}{10^{-12}} )$

$2=log\ I+12\ log\ 10$

$I=10^{-10}\ W.m^{-2}$

Now, power:

$P=I.A$

$P=10^{-10}\times \pi\times \frac{8.4^2}{4}$

$P=5.54\times 10^{-9}\ J.s^{-1}$

Hence:

$KE=\frac{1}{2} m.v^2$

$5.54\times 10^{-9}=0.5\times 2\times 10^{-6}\times v^2$

$v=0.07444\ m.s^{-1}$

$v=74.44\ mm.s^{-1}$

(D)

mosquitoes speed in part B is very much larger than that of part C.

7 0

3 years ago

If an object travels 15 metres in 5 seconds, what is the slope of its distance-time graph?

SOVA2 [1]

Answer:

3 m/s

Explanation:

The slope is distance divided by time, also known as 'speed'.

15 meters / 5 seconds = 3 meters per second.

8 0

2 years ago

Radiation emitted from human skin reaches its peak at λ = 960 µm. what is the frequency of this radiation? planck's constant is

Artist 52 [7]

1) The wavelength of the radiation emitted by the human skin is
$\lambda=960 \mu m = 960 \cdot 10^{-6} m$
the frequency of the radiation is related to the wavelength by
$f= \frac{c}{\lambda}$
where $c=3 \cdot 10^8 m/s$ is the speed of light. Plugging numbers into the formula, we find the frequency of the radiation:
$f= \frac{3 \cdot 10^8 m/s}{960 \cdot 10^{-6}m}=3.13 \cdot 10^{11} Hz$

2) The frequency of this radiation is 313 GHz, and its wavelength $960 \mu m$ . If we look at the table of the electromagnetic spectrum
https://en.wikipedia.org/wiki/Electromagnetic_spectrum
We see that we are in the range of visible light (in particular, in the infrared range).
Therefore, the correct answer is 2. visible light .

6 0

3 years ago

Just how small do you think an individual atom is

jok3333 [9.3K]

An atom is probably less than 1 nano-meter in size

8 0

3 years ago

Read 2 more answers