Objective: We will learn about transformers by making measurements and comparing the results with formulas for an ideal transformer. Please refer to Section 13-4 in Chapter 13 of the text (which is available on Blackboard).

Lab Activities:

1. Apply a 1 volt sinusoidal voltage source at 60 Hz to the primary side of your transformer (the 120 V AC plug). Make measurements at the secondary terminals to determine the turns ratio (n) and the "dots" on the primary and secondary sides of your transformer.

   We will see that for an ideal transformer, V₁ / V₂ = N₁ / N₂ = n (see equation 13.36 in the text).

   Try to measure the currents in the primary and secondary windings, and compare with equation (13.39) in the text. (The current ratio is the reciprocal of the voltage ratio.)

2. Repeat step 1 at frequencies other than 60 Hz, and check whether the turns ratio, n, varies with frequency. Please make a plot of n versus frequency in Matlab, where the frequency range spans several decades.

3. Devise measurement procedures that will allow you to estimate the internal resistances of the primary and secondary coils (R₁ and R₂) and the self-inductances (L₁ and L₂). Measure the self-inductances at several frequencies (beginning with 60 Hz) and see if the results change with frequency.
   (Hint: If you apply a signal at one pair of terminals on the transformer and open-circuit the other terminals, then you can measure the inductance of the coil at which the signal is connected. In other words, the coil that is open-circuited will not affect the measurements on the other coil.)

   Do your measurements agree with the "ideal transformer" assumptions? Compare the ratio L₁ / L₂ with the expected value of [N₁ / N₂]² = n² (see equation 13.35 in the text).

4. If you have time, attach a R = 10,000 ohm load resistor to the secondary, and measure the impedance at the primary terminals, Z_in, at various frequencies that span several decades (including 60 Hz). Compare your result with equation (13.40) in the text, which says that the input resistance should be
   R / (n²).

Also, please bring your lab results to class and we may discuss them as we study transformers.