Question

If you accidentally touch the "hot" wire connected to the 120 V line, how much current will pass through your body?

Answer 1

Complete Question:

You are on an aluminum ladder that is standing on the ground, trying to fix an electrical connection with a metal screwdriver having a metal handle. Your body is wet because you are sweating from the exertion; therefore, it has a resistance of 1.60 kΩ .

(a) If you accidentally touch the "hot" wire connected to the 120 V line, how much current will pass through your body?

(b) How much electrical power is delivered to your body?

Answer:

(a) 0.075A

(b) 9W

Explanation:

The voltage (V) passing across or supplied to a body is directly proportional to the current (I) flowing through the body as stated by Ohm's law. i.e

V ∝ I

=> V = I x R                 ----------------------(i)

Where;

R = constant of proportionality called resistance of the body

(a) As stated in the question;

The body is wet and thus will conduct electricity and has the following;

V = voltage supplied = 120V

R = resistance of the wet body = 1.60kΩ = 1.6 x 1000Ω = 1600Ω

Substitute these values into equation(i) as follows;

120 = I x 1600

Solve for I;

I = $\frac{120}{1600}$

I = 0.075A

Therefore the amount of current that will pass through your body is 0.075A

(b) Electrical power(P), which is commonly measured in Watts(W), delivered to a body is the product of the current(I) and voltage (V) supplied to the body. i.e

P = I x V           ---------------------(ii)

Where;

I = 0.075A   [as calculated above]

V = 120V     [given in the question]

Substitute these values into equation (ii) as follows;

P = 0.075 x 120

P = 9W

Therefore, the electric power delivered to your body is 9W