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2 years ago

Heike Onnes noticed that pure, solid _____ could be cooled to 4.2 K and have no resistance.

Physics

1 answer:

Marrrta [24]2 years ago

6 0

Answer: Mercury

Explanation:

Did it on edg

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The H line in Calcium is normally at 396.9nm. however, in a star’s spectrum it is measured at 398,1 nm. How fast is the star mov

konstantin123 [22]

H line of Calcium spectrum is normally given as 396.9 nm

Now from a distant star we measured it as 398.1 nm

So here this change in the wavelength of distant star is due to Doppler's effect of light as per which when source of light moves towards the observer then the frequency of light received will appear different from its actual frequency

So here we can say as per Doppler's effect of light

$\frac{\Delta \nu}{\nu_0} = \frac{v}{c}$

$\frac{\nu' - \nu}{\nu_0} = \frac{v}{c}$

$\frac{\frac{1}{\lambda} - \frac{1}{\lambda'}}{\frac{1}{\lambda}} = \frac{v}{c}$

$\frac{\lambda' - \lambda}{\lambda'} = \frac{v}{c}$

given that

$\lambda' = 398.1 nm$

$\lambda = 396.9 nm$

$c = 3 * 10^8 m/s$

$\frac{398.1 - 396.9}{398.1} = \frac{v}{3*10^8}$

$v = 3*10^8 * \frac{1.2}{398.1}$

$v = 9.04 * 10^5 m/s$

so the start is moving away with speed 9.04 * 10^5 m/s because when wavelength is more than the real wavelength then its frequency is less which mean it is moving away from the Earth

5 0

3 years ago

Dose sound travel faster in a warm room or a cold room? explain your answer

dusya [7]

Answer:Sound travel faster in warm room.

Explanation:The speed of sound depends on the temperature of the medium. Mathematically, the relation between the speed of the sound and the temperature is give by:v=

is the ratio of the specific heats

R is the gas constant

T is the temperature of the medium

We know that the temperature of the warm room is more as compared to the cold room.

So, it is clear that the sound travel faster in a warm room. The particles move faster when the temperature is high.

8 0

2 years ago

Which of Kepler's laws states that planets sweep areas in equal times?

rodikova [14]

Keplers laws states that planets sweep areas in equal times is second

8 0

2 years ago

As light from air to water to glass, it will refract. The best explanation for this would be

diamong [38]

It d I took the test

6 0

3 years ago

Read 2 more answers

A long electric cable is suspended above the earth and carries a current of 345 A parallel to the surface of the earth. The eart

jok3333 [9.3K]

Answer:

0.906 N

Explanation:

Formula for magnetic force acting on current carrying cable:

$F = IBLsin(\theta)$

Where I = 345A is the current in the wire, B = $5.6*10^{-5} T$ is the magnetic magnitude generated by Earth. L = 46.9 m is the cable length. $\theta = 88.2^o$ is the angle between vector B and cable direction.

$F = 345*5.6*10^{-5}*46.9*sin(88.2^o)$

$F = 0.906 N$

7 0

2 years ago