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# Find the resistance of human body?

**Problem 1: A person touches live wire of a 100 watt closed circuit. If supply voltage is 200 volt and total current flow in a circuit (when touches) is 0.55 ampere, then find the resistance of the human body?**

**Solution:** The circuit shown in diagram is similar to a parallel resistive circuit. We are interested to find the resistance of human body. In order to make this problem easy, let’s draw a resistive circuit of given diagram.

Here, R_{B} is resistance of bulb_{.}

R_{H }is Resistance of human body.

As R_{B} and R_{H} are connected in parallel, so 0.55 current will divided into two parts. Total current of the circuit is current flow through R_{B} and R_{H}.

In order to find current through bulb, first we have to calculate its resistance (R_{B}).

**Power (P) = ** **V ^{2}**

**/R**

_{B}**R**=

_{B}**V**

^{2}**/P**

**R**= (200

_{B}*200) / 100*

**x****R**= 400 Ω

_{B}Hence, current through bulb (**I _{B}**

**)**

**I**= V/R

_{B}**I**

I

_{B}= 200/400I

_{B}= 0.5 Amp.As total current flow through circuit is 0.55 and current flow through bulb is 0.5 Ampere. Therefore, current flow through human body (I_{H}) is

I_{H} = 0.55 – 0.5

I_{H} = 0.05 Amp.

The voltage across human body is 200 volt. Hence resistance of human body (R_{H}) is equal to

R_{H} = V/I (because, V = IR)

R_{H} = 200 / 0.05

**R _{H} = 4000 Ω**

**In short, Resistance of human body is 4000 ohms.**

**Problem 2: A person touches live wire of a closed circuit. The supply voltage is 220 volt and total current flow in a circuit (when touches) is 0.60 ampere. If the current flow through bulb is 0.50 then find the resistance of the human body?**

**Solution: **This problem is almost similar to above one. It is more easier to solve. Let us consider R_{B} is resistance of bulb and R_{H }is Resistance of human body.

Given in the question,

Total circuit current (I) = 0.6 Amp

Current flow through bulb (**I _{B}**) = 0.5 Amp

Supply Voltage (V) = 220 V

As we discussed in problem 1, R_{B} and R_{H} are connected in parallel, so 0.55 current will divided into two parts. Total current of the circuit is current flow through R_{B} and R_{H}.

i.e Total current (I) = **I _{B}** + I

_{H }Therefore,

current flow through human body (I

_{H}) is

I

_{H}= 0.6 – 0.5

I

_{H}= 0.1 Amp.

The voltage across human body is 220 volt. Hence resistance of human body (R_{H}) is equal to

R_{H} = V/I (because, V = IR)

R_{H} = 220/ 0.1

**R _{H} = 2200 Ω**

**In short, Resistance of human body is 2200 ohms.**