Answer:
The correct option is "moving electric charges or currents".
Explanation:
Magnetic field is used to define as a field that surrounds a current carrying conductor or moving electric charge by virtue of which it exerts a force on another current carrying conductor or a moving charge itself.
The magnetic field generated by a moving charge is given by
where
q = is the magnitude of charge
v = is the velocity vector of the moving charge
r = is the position vector of the point at which the field is calculated
|r| = is the magnitude of position vector.
Similar the magnetic field generated by a current carrying conductor is given by
where
I is the current
The integration is carried out along the whole length of conductor.
Also since magnetic mono poles do not exist or their existence is not confirmed until now so it is not an appropriate option.
Answer:
11.9 minutes
Explanation:
The journey is 5000 meters long. The time it takes in seconds for the journey at this speed is 5000/7 =714 seconds.
714/60=time in minutes =11.9 minutes approximately.
Answer:When the Moon is in the position shown below, how would the Moon look to an observer on the North Pole? The moon's rotational period is equal to its revolutional period around Earth. This statement is false because at night we see one side and during the day we see the opposite.
Explanation:
Answer:
True
Explanation:
Since acceleration is inversely proportional to mass, decreasing mass will make the object lighter, and thus easier to speed up. So acceleration increases as mass decreases and vice versa
A radar receiver indicates that a pulse return as an echo in 20 μs after it was sent. The reflecting object would be 3000 m away .
Phenomenon of hearing back our own sound is called an echo. It is due to successive reflection of sound waves from the surfaces or obstacles of large size. To hear an echo, there must be a time gap of 0.1 second in original sound and the reflected sound.
Given
time = 20 μs = 20 * 
s
let distance to the reflecting surface be = x
total distance travelled by pulse will be = 2x
speed = 3.0 × 
m/s
distance = speed * time
2x = 3.0 × * 20 *
x = 3000 m
The reflecting object would be 3000 m away
To learn more about echo here
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