Power Math: Finding Current & Power Dissipated through Person

  • Thread starter Thread starter Tcat
  • Start date Start date
  • Tags Tags
    Power
Click For Summary
SUMMARY

The discussion focuses on calculating the current and power dissipated through a person's body when exposed to a power supply. The person has a resistance of 13.0 kiloohms and is subjected to a potential difference of 16.0 V, with an internal resistance of the power supply at 2100 ohms. The correct current through the body is calculated as 1.06×10−3 A using the formula I = V/(Rp + Ri). To find the power dissipated, the appropriate formula is P = I2R, rather than P = IV, which calculates the power delivered by the supply instead of absorbed by the body.

PREREQUISITES
  • Understanding of Ohm's Law and circuit analysis
  • Familiarity with electrical resistance and power calculations
  • Knowledge of voltage division in circuits
  • Basic concepts of electrical safety and human body resistance
NEXT STEPS
  • Study Ohm's Law and its applications in circuit analysis
  • Learn about voltage division and its relevance in electrical circuits
  • Explore power dissipation formulas, specifically P = I2R
  • Investigate the effects of electrical current on the human body
USEFUL FOR

Electrical engineers, physics students, and anyone interested in understanding the effects of electrical circuits on human resistance and power dissipation.

Tcat
Messages
28
Reaction score
0
Suppose that a person has a resistance of 13.0 kiloohms as part of a circuit which passes through his hands. This person accidentally grasps the terminals of a power supply with a potential difference of 16.0 V.
PART A:If the internal resistance of the power supply is 2100 ohms , what is the current through the person's body?
I calculated the current to be 1.06×10−3 A by using the equation I = V/(R_p + R_i)
PART B: To find the power dissipated in his body I thought you use the equation P = I*V so P =(1.06*10^-3 A)*(16.0V) which gave me 1.70*10^-2 which is wrong. What I am doing wrong??
Thank you for your help
 
Physics news on Phys.org
Firstly I'd just like to comment that the resitance through a person's hand is a bit higher than that. In the mega, if not giga ohm range.

By using P = IV, you have essentiatlly calculated the power DELIVERED by the power suppy instead of the power being absorbed by the person. If you want to use P=IV, then the V must be the potential difference across the person which can be calculated using voltage division. The easier equation would be [tex]P = I^2R[/tex] where you use R of the hands.
 

Similar threads

  • · Replies 3 ·
Replies
3
Views
1K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 2 ·
Replies
2
Views
1K
  • · Replies 8 ·
Replies
8
Views
2K
  • · Replies 2 ·
Replies
2
Views
3K
  • · Replies 9 ·
Replies
9
Views
2K
  • · Replies 2 ·
Replies
2
Views
3K
  • · Replies 6 ·
Replies
6
Views
8K
  • · Replies 1 ·
Replies
1
Views
1K
  • · Replies 6 ·
Replies
6
Views
2K