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physics Advanced Subsidiary (AS) Level Physics.
 
Solved problems for the chapter:
 

Electric Current

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Electric Current
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Example 1.

An electric charge is distributed on a large horizontally placed metal plate with a surface charge density . 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?


A ball is placed above a charged metal plate

    
Example 2.

Calculate the electric current if a charge of 0.2 mC flows through a wire every 5 seconds.

    
3.

Calculate the number of electrons that pass through a wire every second if a current of 1 A flows through the wire.

(The base charge is .)

    
4.

Calculate the electric current of a proton beam if approximately protons flow through a selected cross-section every second.

(The proton base charge is .)

    
5.

Non-conductive cubes with an edge of length 20 cm are placed on a conveyor belt. Each of the cubes is charged with a negative charge of . 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.

    
6.

Raindrops with an average mass of two grams begin to fall from a charged cloud. Calculate the electric current if each drop loses an average of three electrons and a total of 100 kilograms of water falls from the cloud per second. The electron base charge is given as .

    
7.

Calculate the average speed at which electrons move along a round aluminum wire with a radius of 1 mm if a current of 10 amperes is passed through the wire. In aluminum, there are about free electrons and the charge of an electron is .

    
8.

Copper is a monovalent metal, its relative electron mass is 63.5 and its density is . Calculate the number of free electrons in of a copper piece. Avogadro's number is .

    

9.

A metal object is attached to the end of a string. The object is charged with a charge of , and the string starts to rotate in the air at a frequency of 10 Hz. Calculate the average electric current along the orbit.

    
10.

Calculate the average speed of electrons flowing if a current of 10 A is passed through a copper wire of a cross-sectional area of . The density of copper is and its kilomolar mass is 63 kg/kmol. The electron charge is and the Avogadro's number is .