Current_Electricity_Biomedical_Physics_Final.pptx

Current electricity for the ohms law, resistrors and others

1. Current Electricity – Biomedical Physics BPT 1st Year | Silver Oak University

2. Introduction Electricity is the flow of electric charge through a conductor. Essential for biomedical devices like ECG, EEG, and stimulators.

3. Energy Sources for Electricity Primary: Batteries, Solar Cells Secondary: Generators, Power supplies Biomedical: Used in ECG monitors and pacemakers.

4. Electromotive Force (EMF) EMF = W/Q Unit: Volt (V) Battery in ECG machine provides EMF to drive the circuit.

5. Resistance R = V/I (Ohm’s Law) Factors: Length ↑, Area ↓, Material ρ, Temperature ↑

6. Current and Intensity Current (I) = Q/t (Ampere) Represents charge flow per second. Used in EMG, EEG.

7. Ohm’s Law V = I × R Graph: Straight line (V vs I) If R=5Ω, V=10V ⇒ I=2A.

8. Resistance in Series R_total = R₁ + R₂ + R₃ Same current flows through all resistors.

9. Resistance in Parallel 1/R_total = 1/R₁ + 1/R₂ + 1/R₃ Voltage is same across branches.

10. Comparison: Series vs Parallel Series: Same I, Voltage divides Parallel: Same V, Current divides Applications: Voltage divider, Load sharing.

11. Devices for Regulating Intensity Devices that adjust current flow. Examples: Rheostat, Potentiometer.

12. Rheostat: Construction & Working A variable resistor with a sliding contact. Adjusts effective resistance to control current.

13. Electric Energy W = V × I × t (Joule) Represents total electrical work done.

14. Electric Power P = V × I = I²R = V²/R (Watt) Represents rate of electrical work.

15. Thermal Effects of Current (Joule’s Law) H = I²Rt Heat produced ∝ current squared. Used in diathermy and cautery.

16. Application: Diathermy Machine Converts electrical energy to heat for muscle relaxation and improved circulation.

17. Problem Solving 1 Q: A 6V battery drives 2A current. Find R. A: R=V/I=6/2=3Ω.

18. Problem Solving 2 Q: Calculate heat produced when 3A flows through 4Ω for 5s. A: H=I²Rt=3²×4×5=180J.

19. Summary of Formulas Ohm’s Law: V=IR Resistance: R=ρL/A Power: P=VI Energy: W=VIt Heat: H=I²Rt

20. Biomedical Relevance Recap • EMF and resistance in ECG/EEG circuits • Joule’s Law in therapeutic heat devices • Power monitoring in hospitals

21. Summary Points 1. Electric current = charge flow per time 2. Resistance opposes current 3. Ohm’s Law links V, I, R 4. Rheostat regulates current 5. Joule’s Law explains heat

22. Practice Questions 1. Define EMF and Resistance. 2. State Ohm’s Law. 3. Compare series and parallel circuits. 4. Explain Rheostat. 5. State Joule’s Law.

23. Application in Physiotherapy • Electrotherapy • Muscle stimulation • Shortwave diathermy • Device safety

24. Conclusion Understanding current electricity forms the base for all biomedical electrical systems.

25. References 1. Halliday & Resnick 2. K. Sembulingam – Medical Physiology 3. Cromwell – Biomedical Instrumentation