Answer:
<u>a transverse wave consisting of changing electric fields and changing magnetic fields.</u>
Explanation:
An electromagnetic wave is a wave generated by the vibration of perpendicular electric and magnetic fields, which may progate through vacuum (empty space) or a material medium.
All electromagnetic waves propagate at the same speed in vacuum. This speed is approximately 3.0 × 10⁸ m/s. Which is generally referred as the speed of light, but it is the same constant speed of any electromagnetic wave in the vacuum, c.
In general, waves transfer energy when they travel, but only electromagnetic waves can travel in vacuum. The waves that cannot travel in vacuum are named mechanical waves (they need a medium to travel).
There are two types of waves depending on how they propagate: transverse waves and longitudinal waves. The transverse waves travel perperdiculary to the direcction of the vibration, while longitudinal waves travel parallel to the direction of the vibration.
The classical example of transverse waves is a rope that oscilates up and down. The classical example of longitudinal waves is a spring that you pull and push by an end and so it moves forward and back. Sound is also a longitudinal wave.
Answer:
B.The force of friction between the block and surface will decrease.
Explanation:
The force of friction is given by
where 
is the coefficient of friction and 
is the normal force.
When the student pulls on the block with force 
at an angle 
, the normal force on the block becomes
and hence the frictional force becomes
.
Now, as we increase , 
increases which as a result decreases the normal force 
, which also means the frictional force decreases; Hence choice B stands true.
<em>P.S: Choice D is tempting but incorrect since the weight </em>
<em> is independent of the external forces on the block. </em>
Answer:
Because the Moon casts a smaller shadow than Earth does, eclipses of the Sun tightly constrain where you can see them. If the Moon completely hides the Sun, even for a moment, the eclipse is considered total.
Explanation:
