Large capacitors can hold a potentially dangerous charge long after a circuit has been turned off, so it is important to make su
re they are discharged before you touch them. Suppose a 120 μF capacitor from a camera flash unit retains a voltage of 140 V when an unwary student removes it from the camera. If the student accidentally touches the two terminals with his hands, and if the resistance of his body between his hands is 1.8 kΩ, for how long will the current across his chest exceed the danger level of 50 mA?
You are more likely to be shocked during dry days than humid days because during humid days more water is in the air, and water being a good conductor helps the air absorb some of those charges from you, while during dry days there is less water in the air and hence the charges build up since they are not absorbed.
You are less likely to be shocked when you touch a small metal object because smaller metal objects like a paper clip have less space to accept net charge.
