The cloth is soft when it is felt.
Why?The cloth feels soft.
Feels is simple present.
Thus, is + third form is used. ( is + felt )
_____________________________________________To Know More:-This sentence is known as quasi - passive voice.
Why is it known as quasi - passive voice?It is a quasi- passive voice because in this sentence the transitive verb gives the passive sense.
Let us take some examples, to understand it better:-Candy tastes sweet.
Candy is sweet when tasted.
The dress fits well.
The dress is well when fitted.
_____________________________________________