Showing 1 to 10 of 410 Questions

In a particular cathode ray tube, the measured beam current is 30.0 μA. How many electrons strike the tube screen every 40.0 s?
0166 
A teapot with a surface area of 700 cm2 is to be silver plated. It is attached to the negative electrode of an electrolytic cell containing silver nitrate (Ag, + NO3 ). If the cell is powered by a 12.0V battery and has a resistance of 1.80, how long does it take for a 0.133mm layer of silver to build up on the teapot? (The density of s
1944 
Suppose that the current through a conductor decreases exponentially with time according to the equation I (t) = Ioet/r where I0 is the initial current (at t = 0), and + is a constant having dimensions of time. Consider a fixed observation point within the conductor. (a) How much charge passes this point between t = 0 and t = r? (b)
1422 
In the Bohr model of the hydrogen atom, an electron in the lowest energy state follows a circular path 5.29 x 1011 m from the proton. (a) Show that the speed of the electron is 2.19 x 106 m/s. (b) What is the effective current associated with this orbiting electron?
0140 
A small sphere that carries a charge q is whirled in a circle at the end of an insulating string. The angular frequency of rotation is w. What average current does this rotating charge represent?
1290 
The quantity of charge q (in coulombs) that has passed through a surface of area 2.00 cm2 varies with time according to the equation q = 4t3 + 5t + 6, where t is in seconds. (a) What is the instantaneous current through the surface at t = 1.00 s? (b) What is the value of the current density?
1632 
An electric current is given by the expression I (t) = 100 sin (120πt), where I is in amperes and t is in seconds. What is the total charge carried by the current from t = 0 to t = (1/240) s?
0315 
Figure P27.8 represents a section of a circular conductor of nonuniform diameter carrying a current of 5.00 A. The radius of cross section A1 is 0.400 cm. (a) What is the magnitude of the current density across A1? (b) If the current density across A2 is onefourth the value across A1, what is the radius of the conductor at A2?
0165 
The electron beam emerging from a certain highenergy electron accelerator has a circular cross section of radius 1.00 mm. (a) The beam current is 8.00 /A. Find the current density in the beam, assuming that it is uniform throughout. (b) The speed of the electrons is so close to the speed of light that their speed can be taken as c =
0208 
A Van de Graaff generator produces a beam of 2.00MeV deuterons, which are heavy hydrogen nuclei containing a proton and a neutron. (a) If the beam current is 10.0 μA, how far apart are the deuterons? (b) Is the electric force of repulsion among them a significant factor in beam stability? Explain.
0354