1) In the first case, the correct answer is
<span>A.Wavelengths measured would match the actual wavelengths emitted.
In fact, the stars are not moving relative to Earth, so there is no shift in the measured wavelength.
2) In this second case, the correct answer is
</span><span>A.Wavelengths measured would be shorter than the actual wavelengths emitted.
</span>in fact, since the stars in this case are moving towards the Earth, then apparent frequency of their emitted light will be larger than the actual frequency, because of the Doppler effect, according to the formula:

where f0 is the actual frequency, f' the apparent frequency, c the speed of light and vs the velocity of the source (the stars) relative to the obsever (Earth). Vs is negative when the source is moving towards the observer, so the apparent frequency f' is larger than the actual frequency f0. But the wavelength is inversely proportional to the frequency, so the apparent wavelength will be shorter than the actual wavelength.
Answer:

Explanation:
We are given that
Diameter of wire=d=4.12 mm
Radius of wire=r

Current=I=8 A
Drift velocity=
We have to find the density of free electrons in the metal
We know that
Density of electron=
Using the formula
Density of free electrons=
By using Area of wire=

Density of free electrons=
Answer:

In Celsius:

Explanation:
The formula we are going to use is:

Where:
ε is the emissivity
σ is the Stefan constant
is the final temperature of surrounding surfaces
is the required temperature
is the are of surrounding surface
Calculating The area:

σ= 
ε =0.95
=55+273
=328 K
=100 W

In Celsius:

Answer:
Critical thinking is the analysis of facts to form a judgment. The subject is complex, and several different definitions exist, which generally include the rational, skeptical, unbiased analysis, or evaluation of factual evidence
Explanation:
What is the value of the voltage? There must be one somewhere.
This might be too simple minded, but I'll give it a voltage of 10 Volts.
R = voltage / Current
R = 10 / 0.5
R = 20 volts.
Perhaps you could post a diagram if this is a Kirchhoff Law Question.