People who design ad campaigns want you to react to their ads by buying their products. Think about ads you have seen for products. Based on these ads, do you think that advertisers are more likely to design ads that appeal to your mind or your emotions? Explain your answer.

(a) Design a current source able to provide a dc current of 50 mA to an unspecified load. Use a 1N4733 diode $\left(V_{\mathrm{br}}=5.1 \mathrm{V} \text { at } 76 \mathrm{mA}\right).$ (b) Use an appropriate simulation to determine the permissible range of load resistance for your design.

An engineer must design a refrigerator that does 300 J of work per cycle to extract 2100 J of heat per cycle from a freezer whose temperature is $- 10 ^ { \circ } \mathrm { C }$. What is the maximum air temperature for which this condition can be met? Is this a reasonable condition to impose on the design?

Design an experiment that compares three brands of antacids in terms of the speed of symptom relief and amount of acid neutralized.

Design a problem to help other students better understand the amplitude and phase spectra of a given Fourier series.

Design an RL lowpass filter that uses a 40-mH coil and has a cutoff frequency of 5 kHz.

Propose a density-dependent factor that limits growth in the lizard $Zootoca$ $vivipara$ and design an experiment to test this hypothesis.

Using the circuit of the figure and assuming an ideal op amp, design an inverting amplifier with a gain of 26 $\mathrm{dB}$ having the largest possible input resistance under the constraint of having to use resistors no larger than $100\ \mathrm{k} \Omega$. What is the input resistance of your design?

Some DMA controllers support direct virtual memory access, where the targets of I/O operations are specified as virtual addresses and a translation from virtual to physical address is performed during the DMA. How does this design complicate the design of the DMA controller? What are the advantages of providing such functionality?

(a) Design a circuit which produces an output voltage $v_{out}$ proportional to the difference of two positive voltages $v_1$ and $v_2$ such that $v_{out} = 0$ when both voltages are equal, and $v_{out}=10 V$ when $v_1− v_2=1 V.$ (b) Verify your design by analyzing the final circuit.

An experiment is being performed to test the effects of sleep deprivation on memory recall. Two hundred students volunteer for the experiment. The students will be placed in one of five different treatment groups, including the control group. Explain how you could design an experiment so that it uses a randomized block design.

(a) Design a circuit employing only $9\text{ V}$ batteries and standard $5\%$ tolerance value resistors that provide voltages of $1.5\text{ V}$, $4.5\text{ V}$, and $5\text{ V}$ and at least one mesh current of $1\text{ mA}$. (b) Verify your design using PSpice or similar CAD tool.

The circuit is used to drive an LED with a voltage source. The circuit can also be thought of as a current amplifier in that, with the proper design, $i_D>i_1$. (a) Derive the expression for $i_D$ in terms of $i_1$ and the resistors. (b) Design the circuit such that $i_D=12 \mathrm{~mA}$ and $i_1=1 \mathrm{~mA}$ for $v_I=5 \mathrm{~V}$.

Design an experiment that determines the amount of time needed for a person's heart rate to return to normal after exercise.