Under dry conditions, the electrical resistance of the human body between two contact points is typically of the order of which of the following values?

Introduction / Context:
This question checks your awareness of electrical safety and the approximate resistance of the human body in dry conditions. Understanding how much current can flow through the body when it comes into contact with live electrical parts is critical for assessing shock hazards. In general, the human body offers relatively high resistance when the skin is dry and intact, but this resistance can drop drastically when the skin is wet or damaged. Competitive exams often ask for an order of magnitude estimate rather than an exact value.

Given Data / Assumptions:

• The human body is assumed to have dry, intact skin at the points of contact.
• We consider the resistance between two hands or between a hand and a foot in a typical shock scenario.
• The answer choices range from tens of ohms to hundreds of thousands of ohms.
• We are interested in the order of magnitude, not a precise measured resistance.

Concept / Approach:
In electrical safety literature, the resistance of the human body in dry conditions is generally estimated to be tens of thousands to around one hundred thousand ohm or more. The outer layer of skin, particularly when dry, acts as a good insulator. When the skin is wet or broken, resistance can drop significantly, allowing dangerous currents to flow even at low voltages. For dry conditions, values around 100000 ohm are commonly used for simple calculations. Comparing this with the options given, the closest and most appropriate order of magnitude is about 100000 ohm.

Step-by-Step Solution:
Step 1: Recall that dry human skin offers significant resistance to current flow, typically in the kilo-ohm to hundreds of kilo-ohm range. Step 2: Recognise that a resistance as low as 10 ohm would make the body almost like a metallic conductor, which is unrealistic for dry skin. Step 3: Understand that 1000 ohm or 10000 ohm may be reasonable in wet or compromised conditions but are lower than typical dry skin estimates. Step 4: Note that many standard references use a value around 100000 ohm for dry body resistance in safety calculations. Step 5: Select about 100000 ohm as the best approximate value for dry conditions.

Verification / Alternative check:
To appreciate the importance of this resistance, consider a domestic supply of 230 volt. If body resistance is taken as 100000 ohm, the current I = V / R is about 2.3 milliampere, which is noticeable but usually not lethal in a brief contact. If the resistance dropped to 1000 ohm, the current would become 230 milliampere, which can be extremely dangerous. This comparison explains why electrical shocks are much more hazardous when the skin is wet and why the dry resistance is taken to be relatively high in safety discussions.

Why Other Options Are Wrong:
About 10 ohm is far too low and would imply almost metallic conductivity, which does not match the insulating nature of dry skin. About 1000 ohm is closer to typical values for very wet skin or internal body tissues but not for a complete dry body path through the skin. About 10000 ohm is still lower than the commonly quoted dry skin resistance and is more typical of partially wet or compromised conditions.

Common Pitfalls:
Students sometimes underestimate body resistance because they focus only on dangerous current values and not on the insulating role of skin. Others may confuse wet and dry conditions. For exam purposes, it is helpful to remember that dry body resistance is of the order of 100000 ohm, while wet conditions can reduce resistance by an order of magnitude or more. This distinction underlines the importance of keeping electrical equipment and surroundings dry.

Final Answer:
Under dry conditions, the electrical resistance of the human body is typically of the order of about 100000 ohm.