Oxygenated hemoglobin absorbs weakly in the red (hence its red color) and strongly in the near infrared, whereas deoxygenated hemoglobin has the opposite absorption. This fact is used in a "pulse oximeter" to measure oxygen saturation in arterial blood. The device clips onto the end of a person's finger and has two light-emitting diodes-a red (659 nm) and an infrared (979 nm)-and a photocell that detects the amount of light transmitted through the finger at each wavelength. (a) Determine the frequency of each of these light sources. Hz Hz red infrared (b) If 63% of the energy of the red source is absorbed in the blood, by what factor does the amplitude of the electromagnetic wave change? Hint: The intensity of the wave is equal to the average power per unit area as given by 2 I- Emax 2

Problem 9: A current passing through a resistor (R = 25 2) decreases exponentially with time as I(t) = Ioe at where Io = 5.5 A and a = 0.15 s-1. %3D Part (a) Calculate the energy dissipated by the resistor in joules during the first 10 seconds. E = || sin() cos() tan() 7 8 9 НOME E 1^ AL 4 5 6 1 2 3 cotan() asin() acos() atan() acotan() sinh() cosh() tanh() cotanh() + END O Degrees Radians VO BАСKSPАСЕ DEL CLEAR Submit Hint Feedback I give up! Part (b) Calculate the total energy dissipated by the resistor in joules as time goes to infinity.

In the Bohr model of the hydrogen atom, an electron in the 8th excited state moves at a speed of 3.42 x 104 m/s in a circular path having a radius of 3.39 x 10-9 m. What is the effective current associated with this orbiting electron?

(a) In the figure what value must R have if the current in the circuit is to be 1.2 mA? Take 8 = 1.7 V, E2 = 4.3 V, and r1 = r2 = 2.8 Q. (b) What is the rate at which thermal energy appears in R? (a) Number i Units 4 (b) Number i Units

Energetic particles, such as protons, can be detected with a silicon detector. When a particle strikes a thin piece of silicon, it creates a large number of free electrons by ionizing silicon atoms. The electrons flow to an electrode on the surface of the detector, and this current is then amplified and detected. In one experiment, each incident proton creates, on average, 34,000 electrons; the electron current is amplified by a factor of 100; and the experimenters record an amplified current of 3.5 μA. How many protons are striking the detector per second?

When the current in the portion of the circuit shown below is 2.40 A and increases at a rate of 0.420 A/s, the measured voltage is AVab = 8.85 V. When the current is 2.40 A and decreases at the rate of 0.420 A/s, the measured voltage is AVab = 4.90 V. Calculate the values of L and R. HINT: Use a Kirchhoff loop for each of the two scenarios and then simultaneously solve the two equations. Use the signs as given by Kirchhoff's Rules for the emf in the inductor. L = H R = Ω ll L R a 9,

In a certain article, laser therapy was discussed as a useful alternative to drugs in pain management of chronically ill patients. To measure pain threshold, a machine was used that delivered low-voltage direct current to different parts of the body (wrist, neck, and back). The machine measured current in milliamperes (mA). The pretreatment experimental group in the study had an average threshold of pain (pain was first detectable) at ? = 3.19 mA with standard deviation ? = 1.03 mA. Assume that the distribution of threshold pain, measured in milliamperes, is symmetric and more or less mound-shaped. (Round your answers to two decimal places.) (a) Use the empirical rule to estimate a range of milliamperes centered about the mean in which about 68% of the experimental group will have a threshold of painfrom  mA to  mA(b) Use the empirical rule to estimate a range of milliamperes centered about the mean in which about 95% of the experimental group will have a threshold of painfrom  mA to…

Fixing a Radio. You and your team are stranded on a tropical island that hosts a deserted military base. In your efforts to get rescued, you find a radio. However, when you power it up some lights turn on, but the radio does not transmit or receive. You open up the back cover and quickly identify the problem: There is a burnt resistor on the circuit board. You have located some basic electronics tools and supplies, but the charred resistor is unidentifiable, so you do not know what to use for its replacement. There is a crude schematic on the inside of the cover of the radio, but it only gives the value of the current through the part of the circuit with the burnt resistor. You sketch the circuit with all the elements you can identify (see drawing). Assume V₁ = 2.2 V and V₂ = 2.8 V. 8.0 Ω ww 4.0 Ω www V1 V2 2.0 Ω R = ??? 1/18 A (Burnt) (a) Determine the value of the damaged resistor. (b) The next problem is that the resistors that you have found are all 32.0 Q. The available space will…

Lesson4.... light1 $2.002 A Syntax 4.0Ω Σ5.00 x Module6Lesson2A... 12.0V O 13 VIRLab T 8:0 5. Assume that the ammeter in the figure below is removed and the current that flows through the 4.00 path, I3, is unknown. Determine all the currents in the circuit. x Module+7+Lesson... CircuitBuilder x Module+7+Le... P