Determine the Thevenin equivalent resistance (Rt) of the circuit within the box.

A resistor, R, was connected to a circuit box as shown. The voltage, V, was measured. The resistor was changed and the voltage was measured again. The results are shown in the table. Determine the Thevenin equivalent resistance (Rt) of the circuit within the box. See attached file for full problem description.

Determine v(t) for the sinusoidal voltage described

Problem also in attached file. A sinusoidal voltage has a maximum value of 100V, and the value is 10V at t=0. The period is T=1ms. Determine v(t) for the sinusoidal voltage described. A) 100 sin (3.14t + 0.1)v B) 100 sin (6.28t + 6)v C) 100 sin (3142t + 6)v D) 100 sin (6283t + 0.1)v I arrived at "letter C"

Diode DC Models: calculating current and diode parameters

1) Two identical diodes are connected in series with 100 ohms and a 2 V battery such that each diode is forward biased. Let Io = 10fA; n = 1, T = 25 degrees C. Calculate the loop current if (a) ideal diodes are assumed; (b) VD = 0.6 V for each diode; (c) each diode is represented by a piecewise-linear model that is exact at ID = 1mA and 10 mA; (d) each diode is modeled by the nonlinear diode equation. 2) A diode operation at T = 300K has 0.4 V across it when the current through it is 10mA, and 0.42V when the current is twice as large. What values of Io and n allow this diode to be modeled by the diode equation?

Diode & transistor models

Can't solve ID = - 4(VGS - 2.5)^2 (mA).

current mirrors

Two transistors used in a current mirror are characterized by βdc = 40, Vo = 0.7 V and RBB = 10k ohms, If R1 = 2.5k ohms, RC = 2k ohms, and VCC = 7.5 V, find VCE and IE for both transistors. I couldn't find the base current to solve the for Vce and IE.