Return to Blog Homepage

MCAT Physics – Electrical Circuits

  • by Kerry Goldstein
  • Feb 09, 2015
  • MCAT Blog, MCAT Physics, MCAT Question of the Day

A circuit with a total resistance of R and a current of I consumes a total power of P across the resistor network. If the electromotive force denoted by ξ does not equal the terminal voltage, which of the following expressions best approximates voltage lost due to internal resistance?

  1. ξ
  2. ξ + IR
  3. ξ – I2R
  4. ξ – P/I

 

 

Explanation

This question is testing your understanding of electrical circuits and the relationship between current, voltage, power, and resistance. The question stem assigns each of these variables to the circuit described. Additionally, the question stem states that the electromotive force does not equal the terminal voltage, which is the voltage consumed by the resistors. Therefore, the difference between the EMF (ξ) and the terminal voltage (V) will equal the voltage lost to internal resistance.

Internal resistance = ξ – V

Since that is not an option, you must consider what else V is equal to:

(1) V = IR

(2) V = P/I

Substituting (2) into the equation above gives you answer choice D.

 

 

Want more MCAT practice?

We’ve got options for every schedule and learning style!

From the best online MCAT course created by top instructors with 524+ MCAT scores to the most representative full-length practice exams and private tutoring, we can custom tailor your MCAT prep to your goals!

Not sure which option is right for you? Schedule a free MCAT consultation with an MCAT Advisor using the form below. No obligation, just expert advice.

Schedule My Free Consultation

Submit a Comment