Flow cytometry, illustrated in Figure P20.750, is a technique used to sort cells by type. The cells are placed in a conducting saline solution which is then forced from a nozzle. The stream breaks up into small droplets, each containing one cell. A metal collar surrounds the stream right at the point where the droplets separate from the stream. Charging the collar polarizes the conducting liquid, causing the droplets to become charged as they break off from the stream. A laser beam probes the solution just upstream from the charging collar, looking for the presence of certain types of cells. All droplets containing one particular type of cell are given the same charge by the charging collar. Droplets with other desired types of cells receive a different charge, and droplets with no desired cell receive no charge. The charged droplets then pass between two parallel charged electrodes where they receive a horizontal force that directs them into different collection tubes, depending on their charge. Figure P20.75 Nozzle Liquid Cells stream Laser probe Charging collar Deflection- plates Collection tubes Screenshot Question #1 (Flow Cytometry): I If the charging collar has a positive charge, the net charge on a droplet separating from the stream will be A. Positive. B. Negative. C. Neutral. D. The charge will depend on the type of cell. Question #2 (Flow Cytometry): | Which of the following describes the charges on the droplets that end up in the five tubes, moving from left to right? A. +2q, + q, 0, – q, – 29 В. +9, + 2q, 0, — 2q, — 9 С. -q, — 2q, 0, + 2q, +9 D. -2q, - q, 0, + q, + 2g

A capacitor is composed of two metal plates. The two plates have the dimensions L = 0.11 m and W = 0.56 m. The plates have a distance between them of d = 0.1 m, and are parallel to each other.  Part (a)  The plates are connected to a battery and charged such that the first plate has a charge of q. Write an expression for the magnitude of the electric field, |E|, halfway between the plates.  Part (b)  Input an expression for the magnitude of the electric field, |E2|, just in front of plate two.  Part (c)  If plate two has a total charge of q = -1 mC, what is its charge density, σ, in C/m2?

A charged conducting sphere with capacitance, C = 26.7 pF, produces an electric field that points radially outward. At a distance, d = 61.2 cm, from the center of the sphere, the strength of the electric field is E = 71.3 kV/m. (a) What is the radius of the charged sphere? R = m (b) Find the sphere's surface charge density. μC/m² J =

First question

Two large (treat as infinite) parallel conducting plates are charged to t Q as shown by the battery. A proton is released from rest at point A and is measured to be moving with a speed v, = 2 x 105 m/s when at point B. The right plate is then moved closer to the left as shown in the %3D X X rightmost figure. The experiment is repeated. What will be the speed of the proton at point B? A) Greater B) Smaller C) Equal D) Impossible to determine

The next 5 questions all have to do with the diagram shown, on which I have placed an electron at the origin. The grid spacing is 1 Angstrom per small square. Now place an atomic nucleus with 6 protons on positive x-axis, at x = 4.7 Angstroms. How much work did it take you to bring this nucleus in from 1 m away?     15.7 eV     18.4 eV     12.9 eV     23.9 eV

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.

You and your colleagues have been tasked with launching a weather balloon into the Earth's stratosphere via rocket ship. In order to reduce fuel usage to meet with newly imposed fuel-consumption regulations, you are hoping to use the electric interaction between charges to your advantage. You have decided on the design below. You are able to place two Q = 1.98 C charges in the rocket ship and into the launching platform so that they are separated by a distance of yo = 2.93 m. You are allowed enough fuel to boost the rocket to an initial speed of vo = 309 m/s without accounting for the extra boost from the charges. The rocket on its own has a mass of 2.095x104 kg. The more equipment you can attach to your weather balloon (which is inside the rocket), the better. What limit do you put on the mass of the weather balloon and attached equipment? You may want to know the formula for gravitational potential energy for an object of mass m and height h: Egray = mgh, where g=9.81 m/s?. Edge of…

Near the surface of the Earth there is an electric. field of about 150 V/m which points downward. Two identical balls with mass m = 0.620 kg are dropped from a height of 2.30 m, but one of the balls is positively charged with q₁ = 950 μC, and the second is negatively charged with 92 = -950 μC. Part A Use conservation of energy to determine the difference in the speed of the two balls when they hit the ground. (Neglect air resistance.) Express your answer to three significant figures and include the appropriate units. V1 V2 = Submit Provide Feedback Value Request Answer Units ?

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