science

A 24 V battery of internal resistance 4 ohm is connected to a variable resistor. At what value of the current drawn from the battery is the rate of heat produced in the resistor is maximum?

  1. 👍 0
  2. 👎 1
  3. 👁 240
  1. let P be the power delivered to extenal resistance R.

    P= I^2*R= V^2/(4+R)^2 * R
    now will calculus, dP/dR=0 or
    0=V^2/(4+R)^2 + -2RV^2/(4+R)
    0=1-2R(4+R)
    2R^2-8R-1=0
    (R-4)(2R+.25)=0
    R=4 ohms, or R= -1/4 ohms. In real resistsors, resistance can be negative.

    So max current= 24/8=3 amps at max heating of R

Respond to this Question

First Name

Your Response

Similar Questions

  1. Physics

    A 2.0-ohm resistor is connected in series with a 20.0-V battery and a three-branch parallel network with branches whose resistances are 8.0 ohms each. Ignoring the battery's internal resistance, what is the current in the battery?

    asked by leo on April 4, 2013
  2. physics

    a battery has internal resistace of 4ohm and the emf is 12v .The battery used to maintain a current in a resistor of resistance of 20 ohm a)Calculate the current in the circuit b)the potential difference across the ends of the 20

    asked by fredah on June 14, 2016
  3. physics

    A 24V battery of internal resistance of 10ohms is connected to a variable resistor. At what value of current drawn from battery the rate of heat produced by the resistor is maximum? Hence find its value.

    asked by Edwin on March 16, 2010
  4. physics

    a battery has an e.m.f of 6 volts and an internal resistance of 0.4 ohm.it is connected to a 2.6 ohm resistor through a SPST{single pole,single throw}switch.when the switch is closed,the potential difference between the terminals

    asked by komal yaseen on December 31, 2014
  5. science past year

    1.1. A resitance of 1.5ohm is connected in parallel with a resistance of 3 ohm. This combination is connected in series with a resistance of unknown resistance of value R. The circuit is then connected acress a 10 V supply.

    asked by kamil on March 10, 2015
  6. Physics

    A 30 ohm resistor is connected in parallel with a variable resistance R and the parallel combination is then connected in series with a 5 ohm resistor, and connected across 120 volt source. Find the minimum value of R if the power

    asked by Mycah on March 25, 2017
  7. electrical

    A 20v battery with an internal resistance of 5ohm is connected to a resistance of x ohm if an additional 6ohm resistance is connected across the battery find the value of x so that the power supplied externally by the battery

    asked by Anonymous on March 6, 2017
  8. physics

    A 30 ohm resistor is connected in parallel with a variable resistance R. The parallel combination is then connected in series with a 6 ohm resistor and connected across a 120 V source. Find the minimum value of R if the power

    asked by Oscar on March 25, 2017
  9. Physics

    Three resistance of 8,12, and 24 ohms are in parallel. This combination is in series with another parallel of 10,10, and 20 ohms. The whole combination is then connected to a battery of 16.6 volts. If the current through the 20

    asked by Mycah on March 13, 2017
  10. Please help asap science

    1. An electrical circuit consists of a battery with 2 cells,each with an EMF of 12 volts and an internal resistance of of 0.4 ohms,connected in parallel. An ammeter with an internal resistance of 0.15 ohms is connected in series

    asked by Sarah on April 7, 2015

More Similar Questions