Dumbell Curl

 

This workout focuses on your biceps. In order to execute this work out; you first pick up two dumbells, one for each hand, lock your elbows into your sides, and then rotate the dumbells around your elbos from bottom two top. Torque is very evident in this work out, here is a diagram.

 

here is a picture of someone doing the workout to make this explanation clearer.

 

So as the angle changes your biceps feel different amounts of force, when your forearm is sticking out perpendicular from your body you should be feeling maximum amount of torque, on the other hand when your arm is hanging or curled all the way up the torque is minimized.