How are electromagnetic waves are different than mechanical waves?
select all that apply.

a. electromagnetic waves are self-propagating and mechanical waves are not.
b. electromagnetic waves require a medium to travel and mechanical waves do not.
c. electromagnetic waves do not require a medium and mechanical waves do require a medium to travel.
d. electromagnetic waves are always transversal, while mechanical waves can be transverse, longitudinal, or torsional.

Option 'A', 'C', and 'D' are correct.

Explanation:

The most important difference between electromagnetic waves and mechanical waves is :

Mechanical waves needs medium of material for their propagation whereas electromagnetic waves do not need any medium for their propagation.

Like sound waves needs medium to travel so it is considered as mechanical waves.

So, electromagnetic waves are self propagating whereas mechanical waves do not.

Electromagnetic waves travel as transverse wave whereas mechanical waves can be longitudinal and transverse or torsional.

Hence , option 'C' , 'A' and 'D' are correct.

when heated, the valance electrons increased their speed and transferred the heat from electron to electron.   i just took the test.