BIOM 121 1nd EditionExam # 1 Study Guide Lectures: 1 - 10Lecture 1 (Mon 1/13/14)Chapter 17: Electric Charge and Electric FieldSection 1- What are the units of electric charge?- It is measured in coulombs where 1 electron equals -e=1.6E-19C and 1 proton is +e Section 2- What are conductors and insulators?- Conductors allow charge to move throughout them while insulators do notSection 4- What is coulomb’s law? What is the law of superposition?- The law of interacting point electric charges F= (kq1q2)/r^2 where like charges repulse each other and opposite charges attract- When 2 charges exert a force on a third charge, the force on the third charge is the vector sum of the 2 chargesLecture 2 (Wed 1/15/14) Section 5- What is an electric field? What is the relationship between charge, electric field and electric forces?- It is the vector sum of all the fields. Electric fields begin at +q and end at –q.- If the charge is positive the field and force are in the same direction, if negative they are oppositeSection 6- How can you calculate electric fields?- Electric force (F)= charge (q)x electric field (E) - E= mg/q- Equation for electric field due to point charge- Magnitude of the field E= k|q|/r^2Lecture 3 (Fri 1/17/14)Section 7- What is the relationship of electric field lines and the strength of the field? What are some important things to know about field lines?- The greater E(strength of field) is the closer the field lines are to each other.- They never intersect, at a point the electric field is always tangent to the field lines, and they point away from positive charges (opposite for – charge) Section 8- What is the difference between gauss’s law and coulombs? How is Gauss’s law relatedto Electric flux?- Coloumb’s finds the field at point p caused by a single charge while Gauss’s finds extendedcharge on a Gaussian surface from an assembly of q’s using the superposition law- Electric flux is the area multiplied by the magnitude of the electric field. Gauss’s law is based on the fact that the total electric flux out of an enclosed surface is proportional to the total electric charge of the inside of the surface: sumExArea=4pik(Qenclosed)= (Qenclosed)/(Eo)= total flux out of a surfaceSection 9- What is the charge in a conductor?- The electric field is always zero within a conductor. The charge remains on the outside of the surface; however if there is another surface within the Gaussian surface the cavity will have a –q chargeLecture 4 (Wed 1/22/14)Chapter 18: Electric potential and capacitanceSection 1- How can you find the electric potential energy?- When using a point charge U (potential energy)= kqq’/r if both q’s are the same sign thenthey will repulse and positive work is done, the opposite occurs of they have opposite signsSection 2- How is electric potential found?- Potential (ie electric potential – V) is V=U/q or the potential energy per charge. It is measured in J/C also known as voltsSection 3- What is an equipotential surface?- As the title states it is a surface where the potential is the same across the surface. This means that a test charge is the same at any point so the electric field lines are always perpendicular to the surface. Conducting surfaces are always equipotentialLecture 5 (Mon 1/24/14)Section 5- What is capacitance?- It is measured in a farad (coulomb/Volt) consequently it measures the charge to the potential difference in conductors.Section 6-What happens to capacitors in series and in parallel?- In a series potential differences add (V1+V2=VEQ), (1/Ceq)=(1/Ceq1)+(1/Ceq2) and Q1=Q2=Qeq V=Q/C- When parallel charges add (Q1+Q2=Qeq), Ceq=C1+C2 and V1=V2=Veq V=Q/C Lecture 6 (Mon 1/27/14)Section 7- How do you calculate electric field energy?- This value corresponds to the potential energy of the capacitor as well as the work required to charge a capacitor. U= 0.5CV^2= (V/2)QSection 8- What is a dielectric?- A nonconducting material. Dielectric constants (K= Cnew/Coriginal) are calculated and can be used to determine the dielectric effect of the potential difference and electric field by dividing the original V and E by the K.Lecture 7 (Wed 1/29/14)Chapter 19: Current, resistance, and direct-current circuitsSection 1- What is current (I)?- It is the motion of charge from one point to another and is measured in amperes- I(current)=(delta Q)/(delta t)- Current always moves in the direction of the positive chargeSection 2- What is resistance and Ohm’s law? What is resistivity? What is an ohmic resistor anda semiconductor dioide?- Resistance is the the proportion of potential difference (V) to the current in a conductor (I)and is measured in Ohms. Ohm’s law defines the proportionality R=V/I- Resistivity is the resistance proportional to the length and inversely proportional to the cross sectional area of a cylinder conductor R=p(conduction property)L(length)/A(area) and is measured in Ohm(m). If the L is doubled then the V is doubled and if the A is doubled then the I is doubled.- An ohmic resistor is when current is proportional to voltage at a temperature and a semiconductor diode is a non ohmic resistor meaning that voltage does not increase linearly and the resistance is dependent on the direction of the current.Section 3- How can a steady current be achieved? What is electromotive force? How does resistance affect emf?- For a steady current the circuit must be complete or closed.- It is the force that moves charge from low to high potential and is called emf and measured in V. And the potential difference from a point a to b equals the electromotiveforce=IR. In an ideal circuit this relationship allows a circuit to work because the potential difference drives the emf.- Internal resistance decreases the Vab so Vab ends up being less than emf (Vab=emf-Ir) this relationship culminates as I= emf/(R+r) where R + r is the total resistance Lecture 8 (Fri 1/31/14)Section 4- What are the key relationships of energy and power in electric circuits? What is power? What is the relationship between electric energy put in, power put out, and heat dissipating?- Work= the change in charge times the potential difference if Vab is + then the work is + because the potential difference is going from high to low. Work is also expressed as thecurrent times the potential difference times the change in time - Power (P) is the rate of energy transferred or the rate of work being done and is measuredin Watts P=VabI- The