· Does your predicted value of internal resistance agree with the measured value? Why, or why not?
Added by Andrea D.
Step 1
Step 1: State the predicted value of internal resistance (from your model or calculation) and the measured value (from your experiment). Show more…
Show all steps
Your feedback will help us improve your experience
Yaqub Khan and 70 other Physics 101 Mechanics educators are ready to help you.
Ask a new question
Labs
Want to see this concept in action?
Explore this concept interactively to see how it behaves as you change inputs.
Key Concepts
Recommended Videos
(III) What internal resistance should the voltmeter of Example $19-15$ have to be in error by less than 3$\% ?$
THE EMF AND INTERNAL RESISTANCE OF A SOURCE Aims The aims of the experiment are to determine: a) the emf, E, and internal resistance, r, of a cell; b) the condition for maximum power transfer. Method The small box provided contains a cell of emf E and internal resistance r. Using this cell, an ammeter (with negligible resistance), a variable (but known) resistance (R) and a plug key connect the circuit as shown below. Note the meter polarity. Does it matter in what order the components are connected? Explain. In this experiment I is the dependent and R is the independent variable. Is this correct? Explain. Write down the equation for E in terms of the current, I, the external resistance, R, and the internal resistance of the cell, r. Show that equation (E2.1) can be rearranged into a form suitable for plotting a straight-line graph: 1/I = R/E + r/E Explain what should be plotted against what in order to get a straight-line graph, and what you can determine from the slope and the intercepts on both axes. Is it necessary to show the origin on the graph if both intercepts are to be read off? Explain. Take current readings for values of R ranging from 20 ̆ to 100 ̆ in steps of 20 ̆, and then up to 400 ̆ in steps of 50 ̆. (Do not have R < 20 ̆, as this would draw too much current from the battery) Tabulate your readings and the quantities that you calculate from them in the table below. You should convert the milliammeter readings to amperes. Included also is a column for the power dissipated in the external resistance P = I^2 R. R (̆) I (mA) 1/I (A^-1) P = I^2 R (W) 20 75.3 40 66.0 60 60.3 80 53.4 100 48.8 150 41.5 200 35.2 250 28.2 300 20.0 350 13.1 400 0.0 Analysis (a) Plot the straight-line graph suggested by equation (E2.2). N.B. Make sure that you can read a sufficiently large negative intercept on the R axis. From the graph, showing your calculations, determine E and r (the latter in two ways). (b) Plot P against R. Determine the value of R for which P is a maximum. Compare this value with that of r. What do you conclude from this comparison? Explain whether or not this graph should go through the origin.
Linda W.
Internal resistance of a battery: The data in a typical measurement is shown. Make a suitable graph and determine the internal resistance and emf of the battery. The equation you will fit is V = IR = E - Ir. R in ohms: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 Current (I) in amps: 1.44, 0.93, 0.70, 0.54, 0.46, 0.40, 0.34, 0.30, 0.27, 0.24 Voltage (V) in volts: 2.30, 2.57, 2.70, 2.79, 2.85, 2.88, 2.92, 2.94, 2.96, 2.98
Adi S.
Recommended Textbooks
University Physics with Modern Physics
Physics: Principles with Applications
Fundamentals of Physics
Transcript
18,000,000+
Students on Numerade
Trusted by students at 8,000+ universities
Watch the video solution with this free unlock.
EMAIL
PASSWORD