PHYS 102 1nd EditionExam # 2 Study Guide Lectures: 15-22Lecture 15 (September 24)RC Circuits Why are RC Circuits referred to as they are? What is the equation used to calculate charge? Derive Capacitance into time. How do you calculate the interval of time required for a capacitor to reach its charge? In RC Circuits, the R is significant in that it spends energy and the C is significant in that it stores electric energy. The equation used to calculate charge is q = Q(e-t/RC). You can derive Capacitanceinto time by using the following method: C = Q/V  (V/I)*(Q/V) = Q/I = t. You can calculate the interval of time required for a capacitor to reach its charge by using this equation: q = Q(e-t/RC). An example of this would be: A charge capacitor is connected to a resistor and a switch. The circuit has a time constant of 1.10 seconds. Soon after the switch is closed the charge on the capacitor is 70% of its original charge. Find the interval required for the capacitor to reach this charge. q = Q(e-t/RC)  (70/100)Q = Q(e-t/RC)  0.7 = e-t/RC  ln (0.7) = -t/1.10  t = 1.5 ln(0.7)Lecture 16 (September 26)RC Circuits ContinuedWhat is the difference between a RC Circuit charging and discharging? An RC Circuit that is charging will require use of the following equation: q = Q(1- e-t/RC). While an RC Circuit that is discharging will require the use of the following equation: q = Q(e-t/RC). Lecture 17 (October 1) Magnetism What is an MRI? Why are human bodies effectively magnets? If you split a magnet is there a monopole magnet? What is declination? Is a neutron or non-charged particle repelled? An MRI is a strong magnet. Every electric current (moving charges) generates a magnetic field. Thus, currents in human body are effectively magnets. Each electron, in the atoms, is effectively two magnets. If you split a magnet, two new magnets are produced, meaning there is NO monopole magnet. Declination is the angle between the axis of rotation and the magnetic axis. Neutrons have no charge; therefore they are not magnets and cannot be repelled. Lecture 18 (October 6)Calculating Magnetic Fields What unit is used for magnetic fields, B, or magnetism? What equation can be used to calculate the magnetic field produced by a straight wire carrying current? What equation can be used to calculate a magnetic field produced by a solenoid? What equation can be used to calculate an external magnet (B’) that will apply a force on a moving charge (q)? What equation can be used to calculate an external magnet (B’) that will apply a force on a straight wire carrying current? T (tesla) is the unit used for magnetic fields. The following equation can be used to calculate themagnetic field produced by a straight wire carrying current: B = 0i/2r. The following equation can be used to calculate a magnetic field produced by a solenoid: B=0ni ; where n = N/L. The following equation is used to calculate the amount of force that an external magnet will apply on a moving charge (q): F = q v B’ sin . The following equation is used to calculate the amount of force that an external magnet (B’) will apply on a straight wire carrying current: F = I L B’ sin .Lecture 19 (October 8) Calculating Magnetic Fields Continued How can you fully understand how to calculate the amount of force an external magnet will apply on a straight wire carrying current? You can fully understand how to calculate the amount of force an external magnet will apply on a straight wire carrying current by practicing problems in which you do so. A good example is onpage 682, #37. In order to calculate the amount of force an external magnet will apply on a straight wire carrying current you can use the equation: F = I L B’ sin . Lecture 20 (October 10) Understand magnetism between objects. Played with magnets; no notes. Lecture 21 (October 15) Magnetic Flux How do you calculate magnetic flux? How do you calculate induced current (voltage)? What is Faraday’s Law? You can calculate magnetic flux (), by using the following equation: BA cos  = . You can calculate induced current by using the following equation: = f-i. Faraday’s law is  = -N(/t). It calculates the induced voltage, by using the values given for the number of loops, induced current, and the time during the change.Lecture 22 (October 17)Exam 2 Recap What is the equation used to calculate induced voltage for a strip or wire? You can use the following equation to calculate induced voltage for a strip or wire:  = B v