Physics Electrostatics Level: High School
Electric Field
Which one of the following statements is true concerning the spacing of the electric field lines in the vicinity of two point charge of equal magnitude and opposite sign ?a) It indicates the direction of the electric field
b) It does not depend on the magnitude of the charges.
c) It is large when the magnitude of the charges is large.
d) It indicate the relative magnitude of the electric field
e) It is small when the magnitude of the charges is small .
Physics Electrostatics Level: High School
Electric Field
At which point (or points) is the electric field zero N/C for the two point charges shown on the x axis ?a) The electric field is never zero in the vicinity of these charges.
b) The electric field is zero somewhere on the x axis to the left of the +4 q charge .
c) The electric field is zero somewhere on the x axis to the right of the -2q charge .
d) The electronic field is zero somewhere on the x axis between the two charges , but this point is nearer to the -2q charge
e) The electric field is zero at two points along the x axis ; one such points is to right of the -2q charge and the other is to the left of the +4q charge .
Physics Electrostatics Level: High School
Four point charges , each of the same magnitude , with varying signs are arranged at the corners of a square as shown . Which of the arrow labeled A,B,C and D gives the correct direction of the net force that act on the charge at the upper right corner ?a) A
b) B
c) D
d) D
e) The net force on that charge is zero .
Physics Electrostatics Level: High School
Consider three identical metal sphere A , B, C . Sphere A carries a charge of -2.0 microC : sphere B carries a charge of -6.0 micro C ; and sphere C carries a charge of +5.0 microC . Sphere B and C are then touched and separated . Does sphere C end up with an excess or a deficiency of electrons and how many electrons is it ?a) Deficiency , 6 x 10^13
b) Excess, 3 x 10^13
c) Excess, 2 x 10^13
d) Deficiency, 3 x 12^12
e) Deficiency , 1 x 10^12
Physics Electrostatics Level: High School
Electrostatic Induction
A charged conductor is bought near an uncharged insulator . Which one of the following statements is true ?a) Both objects will repel each other .
b) Both objects will attract each other .
c) Neither object exerts an electrical force on the other
d) The object will repel each other only if the conductor has a negative charge .
e) The object will attract each other only if the conductor has a positive charge
Physics Electrostatics Level: High School
A conducting sphere has a net charge of -4.8 x 10^-17 C . What is the approximate number of excess electrons on the spherea) 100
b) 200
c) 300
d) 400
e) 500
Physics Electrostatics Level: High School
Capacitance
John wants to replace the arrangement of capacitors shown in the figure at “click here” with a single capacitor such between points a and b the capacitance stays the same . What capacitance should this capacitor have ?C1 = 5 micro F , C2 = C3 = 4 micro F , C4 = 6 micro F .
Physics Electrostatics Level: High School
Capacitance
(i) The plates of a parallel-plate capacitor are in vacuum , 5.00 mm apart , and are circular in shape with a radius of 17.0 cm . The plates have charges of +- 37.4 micro C . what is the voltage across the plates and capacitance of the capacitor ?
(ii) In the above mentioned capacitor , a dielectric material, strontium titanate , is placed between the plates such that the voltage reduces to 750 V . What is the relative permittivity of the dielectric ?
Physics Electrostatics Level: High School
Gold Leaf Electroscope
(i) A force F exists between two charges , Q1 and Q2 that are a distance r apart . If charge Q1 is halved , and the distance r is increased by a factor of 4 , how much the charge Q2 be changed so that the force remains the same ?
(ii) A conducting rod is earthed while a negatively charged object is held next to one end (without touching it ) such that the rod becomes charged . This charged rod is then brought into contact with the gold-leaf electroscope . The conducting rod is then removed . As a result of this , will the gold leaves become further separated ,or become closer together. Justify your answer .
Physics Electrostatics Level: High School
Capacitor
Find the charge on each capacitor and the voltage across each capacitor .
Physics Electrostatics Level: High School
Capacitor
A capacitor consists of two large parallel charged plates separated by an insulating material , as shown at “click here”.a) What name is given to the insulating material in a capacitor ?
b) In what units would the capacitance of the capacitor be expressed ?
c) What is the basic function of a capacitor ?
d) Use a diagram to show the nature of the electric field between the plates .
e) Would moving the plates of the capacitor further apart increase , decrease or have no effect on its capacitance ?
Physics Electrostatics Level: High School
The operation of a fluorescent light tube involves the transfer of positive mercury ions along the tube under the action of an electric field . At a point P in a fluorescent tube 1.2 meters long , the electric field is 25 NC-1 south , and a positive mercury ion at point P is acted on by a force of 8.0 x 10^-18 N .a) What is the direction of the force acting on the mercury ion ?
b) Calculate the charge on the ion
c) What minimum potential difference must exist between the ends of the tube in order to produce the field of 25 NC^-1 ?
Physics Electrostatics Level: High School
How you would know a nonzero field was present and how you would measure it ?
Physics Electrostatics Level: High School
Beams of high-speed protons can be produced in “guns” using electric field to accelerate the protons .a) What acceleration would a proton experience if the gun’s electric field were 2.00 x 10^4 N/C ?
b) What speed would the proton attain if the field accelerated the proton through a distance of 1.00 cm ?
Physics Electrostatics Level: High School
A plutonium-239 nucleus of radius 6.64 femptometers has an atomic number Z = 94 . Assuming that the positive charge is distributed uniformly within the nucleus , What are the magnitude and direction of the electric field at the surface of the nucleus ? Assume the influence of the positive charge at the nuclear surface is the same as that of a point charge .