The correct answer of this question is : A) Change alternating current into direct current.
EXPLANATION :
As per the question, we are given vacuum tube. Vacuum tube can be of various types. Normally it contains two electrodes called cathode and anode which are enclosed in an evacuated glass chamber . There are also other types of vacuum tubes which contain extra electrodes like control grid .
The vacuum tube can be used as a rectifier. It means that it can be used as an electronic device which will convert alternating current into direct current. It may be a half wave rectifier or a full wave rectifier. Actually the direct current obtained during the rectification of alternating current is pulsating in nature.
Hence, the correct answer is that a vacuum tube can be used to change alternating current into direct current.
This interaction is known as <em>constructive interference</em>. It's a result of linear superposition.
Answer:
The wavelength of the wave is 20 m.
Explanation:
Given that,
Amplitude = 10 cm
Radial frequency 
Bulk modulus = 40 MPa
Density = 1000 kg/m³
We need to calculate the velocity of the wave in the medium
Using formula of velocity

Put the value into the formula


We need to calculate the wavelength
Using formula of wavelength


Put the value into the formula


Hence, The wavelength of the wave is 20 m.
Answer: 1 The correct answer is that CMB radiation was spread uniformly throughout the whole universe.This was related to big band theory because this theory predicts that the universe was a very hot place and as it cooled down it should have been filled with laterally the remnant heat over from the Big Bang called as cosmic microwave background.
Answer: 2 CMB radiation was discovered accidentally when Penzias and Wilson were performing some experiment and they noticed a ' hum' noise that was constantly detected by the antenna even after removing all the disturbing sources.
Then it was realized that it is cosmic microwave background radiation.
Answer:
2.87m
Explanation:
Using the law of gravitation to solve this question
F = GMm/r²
G is the gravitational constant
M and m are the masses
r is the distance between the masses
Substitute the given values
G = 6.67×10^-11 m³/kgs²
M =8.8 x 10^6 kg
m = 5.6 x 10^5 kg
F =440N
400 = 6.67×10^-11×8.8 x 10^6 ×5.6 x 10^5/r²
400r² = 328.698×10
400r² = 3286.98
r² = 3286.98/400
r² = 8.21745
r = √8.21745
r = 2.87m
Hence the distance of separation is 2.87m