One type of ink-jet printer, called an electrostatic ink-jet printer, forms the letters by using deflecting electrodes to steer charged ink drops up and down vertically as the ink jet sweeps horizontally across the page. The ink jet forms diameter drops of ink, charges them by spraying electrons on the surface, and shoots them toward the page at a speed of . Along the way, the drops pass through two horizontal, parallel electrodes that are wide, and spaced apart. The distance from the center of the electrodes to the paper is . To form the tallest letters, which have a height of , the drops need to be deflected upward (or downward) by . What electric field strength is needed between the electrodes to achieve this deflection? Ink, which consists of dye particles suspended in alcohol, has a density of .
The electric field strength needed is
The diameter of drops of ink :
Charge on the droplets :
Speed : 20 m/s.
Dimensions of electrodes : wide, apart.
The distance from the center of the electrodes to the paper : .
Height of the tallest letters :
The drops are deflected upward (or downward) by :
Ink has a density of :
Theory used :
Maximum deflection :
Newton's law :
Field strength :
First, we must locate mass :
Then there's charge :
We now have a value for maximum deflection
We can now calculate acceleration ay using the following relation:
Finally, field strength :
Your physics assignment is to figure out a way to use electricity to launch a small -long plastic drink stirrer. You decide that you’ll charge the little plastic rod by rubbing it with fur, then hold it near a long, charged wire, as shown in FIGURE P23.56. When you let go, the electric force of the wire on the plastic rod will shoot it away. Suppose you can uniformly charge the plastic stirrer to and that the linear charge density of the long wire is . What is the net electric force on the plastic stirrer if the end closest to the wire is away?
Hint: The stirrer cannot be modeled as a point charge; an integration is required.
A point charge is distance r from a dipole consisting of charges separated by distance sT e dipole is initially oriented so that Q is in the plane bisecting the dipole. Immediately after the dipole is released, what are (a) the magnitude of the force and (b) the magnitude of the torque on the dipole? You can assume
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