Which of the following is a characteristic of electromagnetic waves? (2 points)

a they are all invisible.
b they have a dual wave-particle nature.
c they can only travel without a medium.
d they are slower than sound waves.

c They can only travel without a medium.

Explanation:

Electromagnetic waves are made up of electric field and magnetic field.

Here electric field will induce magnetic field and magnetic field will induce electric field.

So this type of field do not require any medium and in vacuum or air the speed of electromagnetic waves are same as speed of light

also we have different range of electromagnetic waves out of which a small range of electromagnetic waves is of visible region in which these waves are visible to us.

so correct answer is

c They can only travel without a medium.

explanation:

as the height from which the ruler was dropped increased, the speed of the ruler at ryan's hand increased.