ou are working in a biology lab during your summer break. Your supervisor asks you to perform an experiment to find the effective spring constant (in N/m) of a partial molecule of DNA (deoxyribonucleic acid). You perform experiments and find that a single straight portion of a DNA molecule is 2.06 µm long. You then perform an activity that charges the ends of the molecule; each end becomes singly ionized: negative on one end, positive on the other. After the ends are charged, the molecule shrinks by 1.20% of its length. ANSWER IN N/m

ou are working in a biology lab during your summer break. Your supervisor asks you to perform an experiment to find the effective spring constant (in N/m) of a partial molecule of DNA (deoxyribonucleic acid). You perform experiments and find that a single straight portion of a DNA molecule is 2.06 µm long. You then perform an activity that charges the ends of the molecule; each end becomes singly ionized: negative on one end, positive on the other. After the ends are charged, the molecule shrinks by 1.20% of its length. ANSWER IN N/m

Principles of Physics: A Calculus-Based Text

5th Edition

ISBN:9781133104261

Author:Raymond A. Serway, John W. Jewett

Publisher:Raymond A. Serway, John W. Jewett

Chapter20: Electric Potential And Capacitance

Section: Chapter Questions

Problem 4P

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You are working in a biology lab during your summer break. Your supervisor asks you to perform an experiment to find the effective spring constant (in N/m) of a partial molecule of DNA (deoxyribonucleic acid). You perform experiments and find that a single straight portion of a DNA molecule is 2.32 µm long. You then perform an activity that charges the ends of the molecule; each end becomes singly ionized: negative on one end, positive on the other. After the ends are charged, the molecule shrinks by 1.25% of its length. Use the particle in equilibrium model to balance the electric and elastic forces on a particle at one of the ends of the molecule. N/m
You are working in a biology lab during your summer break. Your supervisor asks you to perform an experiment to find the effective spring constant (in N/m) of a partial molecule of DNA (deoxyribonucleic acid). You perform experiments and find that a single straight portion of a DNA molecule is 2.06 µm long. You then perform an activity that charges the ends of the molecule; each end becomes singly ionized: negative on one end, positive on the other. After the ends are charged, the molecule shrinks by 1.20% of its length.
You are working in a laboratory, using very sensitive measurement equipment. Your supervisor has explained that the equipment is also very sensitive to electrical discharge from human operators. Specification tables for the equipment indicate that an electrical discharge providing even a very small amount of energy of 250 μJ is enough to damage the equipment. Your supervisor wants to install an apparatus that will be used to remove the electrical charge from individuals’ bodies before they touch the equipment. To do this, she asks you to estimate (a) the capacitance of the human body and determine (b) the charge on the body and (c) the electric potential of the body, relative to a point infinitely far away, corresponding to the energy transfer that will damage the equipment.
Nerve cells in your body can be electrically stimulated; a large enough change in a membrane potential triggers a nerve impulse. Certain plants work the same way. A touch to mimosa pudica, the “sensitive plant,” causes the leaflets to fold inward and droop. We can trigger this response electrically as well. In one experiment, investigators placed electrodes on the thick tissue at the base of a leaf. The electrodes were 3.5 mm apart. When the electrodes were connected to a 47 μF capacitor charged to 1.5 V, this stimulated a response from the plant.a. Eventually, all the charge on the capacitor was transferred to the plant. How much charge was transferred?b. What was the approximate electric field between the electrodes?
A parallel plate capacitor is made of two metallic, circular plates of radius 5.09 cm separated by distance 0.48 mm and contains a glass plate with dielectric constant 8.4. The capacitor is connected to a battery that provides voltage 5.4 V. How much charge is stored on each plate of the capacitor? Provide your answer in nanocoulombs, with a precision of two places after the decimal.
The voltage across the membrane forming a (Biological) cell wall is about 74 mV and the membrane is about 8.7 nm thick. 4c. Molecular changes are sometimes measured with the energy unit of "electron-volt" (eV), where 1eV=1.602×10−19J. For context, a single photon of visible light has an energy of about 2eV. How many eV does it cost to move a doubly-ionized Ca++ ion the hard way across the cell membrane? this is not and will not be graded
If: C1 = 32.9 pF, C2= 29.0 pF, C3= 54.5 pF, C4= 25.4 pF,and V= 27.6 V How much charge is on the top plate of C1? Answer in pC to the nearest pC.
An electric field does 1.69 ✕ 103 eV of work on a carbon nucleus of charge 9.61 ✕ 10−19 C. Find the change in the nucleus' electric potential and electric potential energy in joules. HINT (a) change in electric potential (in V) V (b) change in electric potential energy in joules J
An electric field does 1.05 ✕ 103 eV of work on a carbon nucleus of charge 9.61 ✕ 10−19 C. Find the change in the nucleus' electric potential and electric potential energy in joules. (a) change in electric potential (in V) V (b) change in electric potential energy in joules J
A Geiger-Mueller tube is a radiation detector that consists of a closed, hollow, metal cylinder (the cathode) of inner radius ra and a coaxial cylindrical wire (the anode) of radius rb (see figure below) with a gas filling the space between the electrodes. Assume that the internal diameter of a Geiger-Mueller tube is 3.40 cm and that the wire along the axis has a diameter of 0.205 mm. The dielectric strength of the gas between the central wire and the cylinder is 1.30 106 V/m. Use the equation 2?rℓE = qin ?0 to calculate the maximum potential difference that can be applied between the wire and the cylinder before breakdown occurs in the gas.
Suppose a capacitor consists of two coaxial thin cylindrical conductors. The inner cylinder of radius ra has a charge of +Q, while the outer cylinder of radius rb has charge -Q. The electric field E at a radial distance r from the central axis is given by the function: E = ae-r/ao + B/r + bo where alpha (a), beta (B), ao and bo are constants. Find an expression for its capacitance. First, let us derive the potential difference Vab between the two conductors. The potential difference is related to the electric field by: Vab = Edr Edr Calculating the antiderivative or indefinite integral, Vab = (-aager/a0 + B + bo By definition, the capacitance C is related to the charge and potential difference by: C = Evaluating with the upper and lower limits of integration for Vab, then simplifying: C= Q/( (e-rb/ao - eTa/ao) + ß In( ) + bo ( ))
A Geiger-Mueller tube is a radiation detector that consists of a closed, hollow, metal cylinder (the cathode) of inner radius ra and a coaxial cylindrical wire (the anode) of radius rb (see figure below) with a gas filling the space between the electrodes. Assume that the internal diameter of a Geiger-Mueller tube is 1.95 cm and that the wire along the axis has a diameter of 0.210 mm. The dielectric strength of the gas between the central wire and the cylinder is 1.30 106 V/m. Use the equation 2?rℓE =qin/?0 to calculate the maximum potential difference that can be applied between the wire and the cylinder before breakdown occurs in the gas. [Image] A cross-section of a Geiger-Mueller tube shows an inner anode of radius rb and charge density ? and an outer cathode of radius ra and charge density −?.