The dry human body has an electric resistance of the order of magnitude of 10^4 ohm (10,000 ohm). This resistance can vary depending on factors such as skin moisture, contact area, and individual characteristics. Dry skin offers a relatively high resistance to the flow of electric current due to its insulating properties. The resistance of the human body plays a significant role in determining the effects of electric shocks and electrical safety measures. Higher resistance limits the current flow through the body, reducing the potential harm caused by electric shock. However, it’s important to note that wet or moist conditions can significantly decrease the body’s resistance and increase the risk of electrical injury. Direction: The following item consists of two statements, one labeled as the Assertion (A) and the other as Reason (R). You have to answer this item using the code given below. 274. Assertion (A): In our houses, the current in the A.C. electricity line changes direction 60 times per second. Reason (R): The frequency of alternating voltage supplied is 50 Hz.

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Correct answer: A is false but R is true. Assertion (A) is false: In an alternating current (AC) system the current reverses direction periodically. The rate at which this reversal occurs is determined by the frequency of the supplied AC voltage. The standard AC supply frequency in many countries including India is 50 Hz. The AC completes one full cycle (positive and negative half-cycles) in 1/50th of a second. In one full cycle, the current changes direction twice (once at the positive peak and once at the negative peak). Therefore in a 50 Hz system the current changes direction 2 × 50 = 100 times per second, not 60 times per second. Science and Technology 595 Reason (R) is true: The standard AC frequency in many countries (including India) is indeed 50 Hz. This means that the AC completes 50 cycles per second. 275

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