Answer: d) the presence of solidified lava flows on the Moon
Explanation:
A geological activity means an occurrence of event such as volcanic eruption, earthquake, sedimentation, erosion etc. The revolution of the Moon around the Earth
, the axial tilt of the Moon or the phases of the Moon are not surface features. hence, these events cannot provide the evidence of geological activity in the past of Moon.
The surface features of moon such as Mares, Craters, mountains, Rays and rills are the proof of some geological activity on the Moon. Mares are the dark patches on the moon's surface formed of solidified lava. Due to negligible atmosphere on the moon, the meteors strike its surface and cause craters to form. Thus, the correct answer is d.
Field in this context refers to a region of the space to which corresponds a value.
There is a gravitational field around the earth, because a mass m placed at any point around the earth will be atracted (gravitational force) by it.
There is an electric field in a point when a charge placed there feels an electric force.
The gravitational field is proportional to the value of the mass of the object that produces it.
The electric field is proportional to the magnitude of the charge of the particle that produces it.
The gravitational field is always attractive. The electric field may be attractive or repulsive.
Both fields are proportional to the inverse of the squared distance.
The magnetic field is created when a charge is in movement,i.e a charge in movement will create a magnetid fiedl around it that will act and create a magnetic force over other charge also in movement.
The magnetic field is proportional to the product of the charge times its velocity and inversely proportional to the squared distance. The force generated my be attractive or repulsive.
They are slowed down.
even air is a medium and will slow down waves (slightly) compared to a vacuum/ space
if the wave hits the medium at an angle it can be 'bent' (refracted) like light through a glass prism
Stop cheating learn from ur resources
Let A = i+j+k be a vector and B = 3 be any scalar,
Multiplying A and B,
AB = (i+j+k)3 = 3i+3j+3k
Which is a new vector whose direction is same as the old but it's 3 times greater in length than the old vector(i+j+k).
Now, dividing A and B,
A/B = (i+j+k)/3 =
Which is again a new vector whose direction is same as the old but now it's 1/3 times small in length than the old vector.
Direction is same because we multiplied by positive scalar. If we multiply A by suppose -1, -4, -1000000 or any negative number, it's direction will reverse.
Thus, if we multiply a vector with scalar, it's length increases. If we divide, it shrinks.