Correct Option
The correct option isTap water containing dissolved salts is a good conductor of electricity.
Explanation
The danger of electric shock depends on the magnitude of current flowing through the human body. According to Ohm’s Law, for a given voltage, the current is inversely proportional to resistance. Dry human skin has a high electrical resistance (typically around 100,000 ohms or more), acting as a partial insulator. However, the presence of moisture significantly alters this property.
Detailed Analysis
- Water significantly increases the skin's electrical resistance. is Incorrect: Water does not increase the skin's electrical resistance; rather, it drastically reduces it. When skin is wet, the resistance can drop to as low as 1,000 ohms. This reduction allows a much larger current to flow through the body for the same voltage, leading to severe electric shock.
- Tap water containing dissolved salts is a good conductor of electricity. is Correct: Pure water is a poor conductor of electricity. However, ordinary tap water contains dissolved salts and minerals (ions) which make it a good conductor (electrolyte). When wet hands touch an electrical appliance, this conductive layer of water bridges the gap between the live component and the body, bypassing the high resistance of dry skin and facilitating the flow of electric current.
- Water generates static electricity upon contact. is Incorrect: Static electricity is typically generated by friction between insulators (triboelectric effect). The danger in this context arises from the continuous flow of current (dynamic electricity) from the mains supply, not static discharge.
- Water causes the appliance to overheat. is Incorrect: While water entering an appliance can cause a short circuit and potential overheating, the primary danger to the person touching the appliance is electric shock, not the heating of the device.
Key Takeaway: Tap water contains dissolved ions that make it a good conductor. Touching electrical appliances with wet hands lowers the body's contact resistance significantly, allowing dangerous levels of current to flow through the body.