Answer: (B) They can be penetrated only with longer wavelengths such as radio and infrared.
Explanation:
A dark nebula is a type of interstellar cloud with such a high density that it "hides" the light of the background stars.
It should be noted that these nebulae are composed mostly of hydrogen (the star's primary fuel), and the absence of light (in the visible range of the electromagnetic spectrum) is caused by the interstellar solid dust that constitutes the cloud, which is why they are also called absorption nebulae.
However, <u>if powerful telescopes that detect at long wavelengths, such as infrared and X-rays, it is possible to observe through these nebulae and even observe the existence of young stars.</u>
Answer:
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Explanation:
Answer:


-0.020475 V
Explanation:
= Vacuum permeability = 
= Number of turns of coil = 25
= Number of turns of coil 2 = 300
= Rate of current increased = 
d = Diameter = 2 cm
r = Radius = 
A = Area = 
Magnetic field in the solenoid is given by

Magnetic flux is given by

The average magnetic flux through each turn of the inner solenoid is
Mutual inductance is given by

The mutual inductance of the two solenoids is 
Induced emf is given by

The emf induced in the outer solenoid by the changing current in the inner solenoid is -0.020475 V