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. A spherical ball with radius 
and density 
is brought closer to the plate. What is the least quantity of charge that must be on the ball to make it float above the plate?
.)
protons flow through a selected cross-section every second.
.)
. The cubes touch each other. The belt moves uniformly at a speed of 3 m/s. Calculate the electric current along the belt and determine its direction.
.
aluminum, there are about 
free electrons and the charge of an electron is 
.
. Calculate the number of free electrons in 
of a copper piece. Avogadro's number is 
.
, and the string starts to rotate in the air at a frequency of 10 Hz. Calculate the average electric current along the orbit.
. The density of copper is 
and its kilomolar mass is 63 kg/kmol. The electron charge is 
and the Avogadro's number is 
.
in a conductor is given by the equation shown.
represent in this equation?
. How many electrons pass a fixed point in the wire in a time of 10 hours?
. At end S of the wire, the cross-sectional area is 
. Charge 
takes time 
to pass through end R of the wire. There is a constant electric current in the wire. How much charge will pass through end S in a time interval of 
?
and a diameter of 
. The number density of the free electrons in nichrome is 
. A potential difference (p.d.) of 
is applied between the ends of the wire. What is the average drift speed of the free electrons in the wire?
.
has a number density of free electrons of 
In a given time interval, a charge of 
moves through the wire. What is the average displacement of the free electrons along the wire in this time interval?
, 
and 
as shown, and its volume is 
. Each charge carrier has a charge 
and the number density of the charge carriers in the metal is 
. It takes each charge carrier an average time of 
to pass through the block. What is an expression for the current 
?
?
. What is the average current in the wire?
. A copper wire has diameter 
. What is the average drift speed of the free electrons in the wire when the current in the wire is 
?
, are placed on the edge of an insulating disc of radius 
. The disc rotates at a rate of 
revolutions per unit time.
and contains a total of 
free electrons. When a potential difference is applied across the ends of the wire, the free electrons move with an average drift speed of 
. What is the current in the wire?
with an average drift speed of 
. The current in the wire is 
. There is a current of 
in a copper wire Y of radius 
. What is the average drift speed of the free electrons in copper wire Y?
