1. Which of the following statements for electric field lines are true? (Give ALL correct answers, i.e., B, AC, BCD…) A) E-field lines point inward toward negative charges. B) E-field lines may cross. C) E-field lines do not begin or end in a charge-free region (except at infinity). D) Where the E-field lines are dense the E-field must be weak. E) E-field lines make circles around positive charges. F) A point charge q, released from rest will initially move along an E-field line. G) E-field lines point outward from positive charges. 2. Consider two uniformly charged parallel plates as shown above. The magnitudes of the charges are equal. (For each statement select T True, F False). A) If the plates are oppositely charged, there is no electric field at c. B) If both plates are negatively charged, the electric field at a points towards the top of the page. C) If both plates are positively charged, there is no electric field at b. 3. As shown in the figure above, a ball of mass 1.050 g and positive charge q =38.1microC is suspended on a string of negligible mass in a uniform electric field. We observe that the ball hangs at an angle of theta=15.0° from the vertical. What is the magnitude of the electric field?

## 1. Which of the following statements for electric field lines are true? (Give ALL correct answers, i.e., B, AC, BCD…) A) E-field lines point inward toward negative charges. B) E-field lines may cross. C) E-field lines do not begin or end in a charge-free region (except at infinity). D) Where the E-field lines are dense the E-field must be weak. E) E-field lines make circles around positive charges. F) A point charge q, released from rest will initially move along an E-field line. G) E-field lines point outward from positive charges. 2. Consider two uniformly charged parallel plates as shown above. The magnitudes of the charges are equal. (For each statement select T True, F False). A) If the plates are oppositely charged, there is no electric field at c. B) If both plates are negatively charged, the electric field at a points towards the top of the page. C) If both plates are positively charged, there is no electric field at b. 3. As shown in the figure above, a ball of mass 1.050 g and positive charge q =38.1microC is suspended on a string of negligible mass in a uniform electric field. We observe that the ball hangs at an angle of theta=15.0° from the vertical. What is the magnitude of the electric field?

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a boat is advertised for \$4700 can be bought under the following hire purchase agreement, no deposit charged but loan must be paid off monthly over period of three years. interest is charged at flat rate of 16% per annum what is monthly repayment

## a boat is advertised for \$4700 can be bought under the following hire purchase agreement, no deposit charged but loan must be paid off monthly over period of three years. interest is charged at flat rate of 16% per annum what is monthly repayment

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ELEC 2000 Semiconductor Devices Homework #1 Choose the answer that best completes the statement or answers the question. (1) Assume the valence electron is removed from a copper atom. The net charge of the atom becomes a. 0 b. +1 c. -1 d. +4 (2) The valence electron of a copper atom experiences what kind of attraction toward the nucleus? a. None b. Weak c. Strong d. Impossible to say (3) How many valence electrons does a silicon atom have? a. 0 b. 1 c. 2 d. 4 (4) Silicon atoms combine into an orderly pattern called a a. Covalent bond b. Crystal c. Semiconductor d. Valence orbit (5) An intrinsic semiconductor has some holes in it at room temperature. What causes these holes? a. Doping b. Free electrons c. Thermal energy d. Valence electrons (6) The merging of a free electron and a hole is called a. Covalent bonding b. Lifetime c. Recombination d. Thermal energy (7) At room temperature an intrinsic silicon crystal acts approximately a. A Battery b. A conductor c. An insulator d. Copper wire (8) The amount of time between the creation of a hole and its disappearance is called a. Doping b. Lifetime c. Recombination d. Valence (9) A conductor has how many type of flow? a. 1 b. 2 c. 3 d. 4 (10) A semiconductor has how many types of flow? a. 1 b. 2 c. 3 d. 4 (11) For semiconductor material, its valence orbit is saturated when it contains a. 1 electron b. Equal (+) and (-) ions c. 4 electrons d. 8 electrons (12) In an intrinsic semiconductor, the number of holes a. Equal the number of free electrons b. Is greater than the number of free electrons c. Is less than the number of free electrons d. None of the above (13) The number of free electrons and holes in an intrinsic semiconductor decreases when the temperature a. Decreases b. Increases c. Stays the same d. None of the above (14) The flow of valence electrons to the right means that holes are flowing to the a. Left b. Right c. Either way d. None of the above (15) Holes act like a. Atoms b. Crystals c. Negative charges d. Positive charges (16) An donor atom has how many valence electrons? a. 1 b. 3 c. 4 d. 5 (17) If you wanted to produce a p-type semiconductor, which of these would you use? a. Acceptor atoms b. Donor atoms c. Pentavalent impurity d. Silicon (18) Electrons are the minority carriers in which type of semiconductor? a. Extrinsic b. Intrinsic c. n-Type d. p-type (19) Silver is the best conductor. How many valence electrons do you think it has? a. 1 b. 4 c. 18 d. 29 (20) Which of the following describes an n-type semiconductor? a. Neutral b. Positively charged c. Negatively charged d. has many holes (21) What is the barrier potential of a silicon diode a room temperature? a. 0.3 V b. 0.7 V c. 1 V d. 2 mV per degree Celsius

## ELEC 2000 Semiconductor Devices Homework #1 Choose the answer that best completes the statement or answers the question. (1) Assume the valence electron is removed from a copper atom. The net charge of the atom becomes a. 0 b. +1 c. -1 d. +4 (2) The valence electron of a copper atom experiences what kind of attraction toward the nucleus? a. None b. Weak c. Strong d. Impossible to say (3) How many valence electrons does a silicon atom have? a. 0 b. 1 c. 2 d. 4 (4) Silicon atoms combine into an orderly pattern called a a. Covalent bond b. Crystal c. Semiconductor d. Valence orbit (5) An intrinsic semiconductor has some holes in it at room temperature. What causes these holes? a. Doping b. Free electrons c. Thermal energy d. Valence electrons (6) The merging of a free electron and a hole is called a. Covalent bonding b. Lifetime c. Recombination d. Thermal energy (7) At room temperature an intrinsic silicon crystal acts approximately a. A Battery b. A conductor c. An insulator d. Copper wire (8) The amount of time between the creation of a hole and its disappearance is called a. Doping b. Lifetime c. Recombination d. Valence (9) A conductor has how many type of flow? a. 1 b. 2 c. 3 d. 4 (10) A semiconductor has how many types of flow? a. 1 b. 2 c. 3 d. 4 (11) For semiconductor material, its valence orbit is saturated when it contains a. 1 electron b. Equal (+) and (-) ions c. 4 electrons d. 8 electrons (12) In an intrinsic semiconductor, the number of holes a. Equal the number of free electrons b. Is greater than the number of free electrons c. Is less than the number of free electrons d. None of the above (13) The number of free electrons and holes in an intrinsic semiconductor decreases when the temperature a. Decreases b. Increases c. Stays the same d. None of the above (14) The flow of valence electrons to the right means that holes are flowing to the a. Left b. Right c. Either way d. None of the above (15) Holes act like a. Atoms b. Crystals c. Negative charges d. Positive charges (16) An donor atom has how many valence electrons? a. 1 b. 3 c. 4 d. 5 (17) If you wanted to produce a p-type semiconductor, which of these would you use? a. Acceptor atoms b. Donor atoms c. Pentavalent impurity d. Silicon (18) Electrons are the minority carriers in which type of semiconductor? a. Extrinsic b. Intrinsic c. n-Type d. p-type (19) Silver is the best conductor. How many valence electrons do you think it has? a. 1 b. 4 c. 18 d. 29 (20) Which of the following describes an n-type semiconductor? a. Neutral b. Positively charged c. Negatively charged d. has many holes (21) What is the barrier potential of a silicon diode a room temperature? a. 0.3 V b. 0.7 V c. 1 V d. 2 mV per degree Celsius

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1A. You administer an IV with 3 liters of 50 mM NaCl to a person whose osmolarity is 300 mOsM and whose total body water is 30 L. Fill in the table below: 3 L of 50 mM NaCl Total body ECF ICF Solute (osmoles) Volume (L) Concentration (OsM) 1B. The same person from the previous problem instead is given 1 liter of an IV contained 250 mOsM NaCl and 50 mOsM urea. Com Total body ECF ICF Solute Volume Concentration 2. You isolate intact mitochondria as described in class and equilibrate them in a buffered solution at pH 9, containing 0.1 M KCl and ADP plus Pi but without succinate. You then collect them by centrifugation, and quickly resuspend them in a new buffer at pH 7, without KCl , but with valinomycin (a K+ ionophore). Note: the K+ rushing out will create a huge positive charge differential. a. Describe what happens to proton concentrations in the intermembrane space and the matrix at each step of the study. b. What do you predict will be the result on oxygen consumption and the production of ATP?   3. A negatively charged nutrient (equivalent charge of one electron) is actively transported from the outside to the inside of a cell membrane; i.e. a cell captures energy from the hydrolysis of ATP in order to bring a molecule from the outside of the cell, where it is present at a low concentration, to the inside of the cell, where it is present at higher concentration. If the molecular species to be transported is present at a concentration of 34.5 nM on the outside of the cell, the potential on the outside of the cell is +75 mV, the potential on the inside of the cell is -35 mV, and the efficiency at which energy from the hydrolysis of ATP is captured for this active transport process is 59%, what is the maximum concentration of the transported species that may be achieved inside the cell?   4. . ATP + H2O -> ADP + Pi G0 = -7.3 kcal/mol In a chemical system that has two different solute concentrations, the Gibbs free energy that is available to do work is: ΔG = RT ln [C1/C2], where R and T are the gas constant (2 cal/mol K) and temperature (Kelvin). C1 and C2 refer to the concentrations (e.g. molarities, M) of a solute on different sides of a membrane. (a) For a one unit difference in pH across a cellular membrane, what is the energy (in kcal/mol) that is available to do chemical work? (b) This gradient is to be used to drive the reaction synthesis of ATP from ADP and Pi. A concentration gradient of any solute has potential energy. When the solute is charged, a voltage is also established across the membrane, which also adds to the total potential energy. What fraction of the energy needed to drive the reaction is provided by the voltage across the membrane?

## 1A. You administer an IV with 3 liters of 50 mM NaCl to a person whose osmolarity is 300 mOsM and whose total body water is 30 L. Fill in the table below: 3 L of 50 mM NaCl Total body ECF ICF Solute (osmoles) Volume (L) Concentration (OsM) 1B. The same person from the previous problem instead is given 1 liter of an IV contained 250 mOsM NaCl and 50 mOsM urea. Com Total body ECF ICF Solute Volume Concentration 2. You isolate intact mitochondria as described in class and equilibrate them in a buffered solution at pH 9, containing 0.1 M KCl and ADP plus Pi but without succinate. You then collect them by centrifugation, and quickly resuspend them in a new buffer at pH 7, without KCl , but with valinomycin (a K+ ionophore). Note: the K+ rushing out will create a huge positive charge differential. a. Describe what happens to proton concentrations in the intermembrane space and the matrix at each step of the study. b. What do you predict will be the result on oxygen consumption and the production of ATP?   3. A negatively charged nutrient (equivalent charge of one electron) is actively transported from the outside to the inside of a cell membrane; i.e. a cell captures energy from the hydrolysis of ATP in order to bring a molecule from the outside of the cell, where it is present at a low concentration, to the inside of the cell, where it is present at higher concentration. If the molecular species to be transported is present at a concentration of 34.5 nM on the outside of the cell, the potential on the outside of the cell is +75 mV, the potential on the inside of the cell is -35 mV, and the efficiency at which energy from the hydrolysis of ATP is captured for this active transport process is 59%, what is the maximum concentration of the transported species that may be achieved inside the cell?   4. . ATP + H2O -> ADP + Pi G0 = -7.3 kcal/mol In a chemical system that has two different solute concentrations, the Gibbs free energy that is available to do work is: ΔG = RT ln [C1/C2], where R and T are the gas constant (2 cal/mol K) and temperature (Kelvin). C1 and C2 refer to the concentrations (e.g. molarities, M) of a solute on different sides of a membrane. (a) For a one unit difference in pH across a cellular membrane, what is the energy (in kcal/mol) that is available to do chemical work? (b) This gradient is to be used to drive the reaction synthesis of ATP from ADP and Pi. A concentration gradient of any solute has potential energy. When the solute is charged, a voltage is also established across the membrane, which also adds to the total potential energy. What fraction of the energy needed to drive the reaction is provided by the voltage across the membrane?

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1. A repelling force occurs between two charged objects when the charges are of a. unlike signs. c. equal magnitude. b. like signs. d. unequal magnitude.

## 1. A repelling force occurs between two charged objects when the charges are of a. unlike signs. c. equal magnitude. b. like signs. d. unequal magnitude.

ANS:    B
A capacitor is charged with a battery. Then, with the battery connection maintained the plates are moved closer together. Then results in, a) a decrease in capacitance , b) a decrease in charge on the plates. c) a decrease in the electric fields between the plates. , d) an increase in the energy stored. e) a change in the potential between the plates.