Answer:
B.) by interfering with sound waves
Explanation:
As we know that the interference of sound waves is of two types
1). constructive interference
2). destructive interference
now we know that constructive interference means the resultant intensity will be more than the intensity of interfering waves as here two waves are in same phase.
In destructive interference the resultant of two waves is given by the minimum resultant of the intensity as here the phase of two waves are opposite to each other.
So we will say that
here in case of noise cancelling headphones we know that the phase of noise is always made in opposite phase with the sound which is used to cancelled the noise.
This will reduce the noise and we will get a clear sound
Answer:
D) follows a circular path
Explanation:
This is because the magnetic force F on the charge, q due to the magnetic field B with velocity vector v perpendicular to it, equals the centripetal force acting on the charge.
So, F = Bqv = mv²/r.
So it follows a circular path.
Answer:
The slower the train is moving, the less are the changes of the magnetic flux, thus the eddy currents become weaker.
Explanation:
A magnetic brakes is not a very efficient way of braking when a train is moving slowly because at low speeds, the changes in the magnetic flux are very less and so it causes the eddy current to become weaker.
Let us find the drag force which is proportional to the velocity of two conducting plates.
The EMF that is induced in the eddy currents are : 
The force which is due to the induced magnetic field is, 
Therefore, 
Here, force is directly proportional to the velocity of the two conducting plates.
Therefore, we can say that when the speed of the train is low, the magnetic flux changes are less and thus the eddy currents are weaker.
The answer is 1.9 m
The ideal mechanical advantage (IMA) is the ratio of input distance (ID) to output distance (OD):
IMA = ID/OD
IMA = 2
ID = ramp length = 3.8 m
OD = height = ?
2 = 3.8m/OD
OD = 3.8/2
OD = 1.9 m
Answer:
B. a region of similarly oriented electrons in motion
Explanation:
