1. Chapter 20 Review Which subatomic particle is involved the transfer of an electrical charge? ans: electron Two charged bodies are brought next to each other resulting in a repelling. This means: ans: like charged particles Material that allows for the easy transfer of an electrical charge is called a(n): ans conductor

2. Which statement is more true about a conductor: 1. conductor have a higher density 2. conductor a have delocalized electrons ans: both The type of material that does NOT allow for the free movement of electrons are: ans: insulators Insulators are characterized by: ans: charges do NOT move

3. The causal effect of like charge lining up within a conductor without transferring from that conductor is called: ans: induction “Bleeding off” or expelling excess charges on a substance is called: ans grounding The process of inducing one end of a substance to be more positive is called: ans: polarization

4. Can polarization occur in an insulator? ans: yes When charges are induced in a substance and polarization occurs, what is the net charge on the substance? ans: neutral still What does the term ‘surface charge’ refer to: ans: polarization of an insulator Electrostatic equilibrium on a sphere occurs ans: equally around the sphere

5. Two charged bodies are moved from 1cm to 5 cm apart. What effect will this have on the force between the bodies? ans: inverse square to distance, 4 cm increase or 4 2 = 16 or 1/16 or 16x less F A cubic conductor has an electrostatic charge. Where on the cube will the greater concentration of charge be found? ans: at the corners, charge accumulate at areas that cause greater density of charge

6. With a sphere the accumulation of the charge is on the surface. What is the charge on the electric field everywhere: ans: zero or neutral Where do the charge accumulate in a conductive hollow sphere? ans: on the surface A sharpened pencil has an accumulation of excess e-. Will the charges be equally distributed? NO. Highest density of charge at the smallest area. At the sharpened tip

7. Three charged bodies along the x-axis. At x= 0 cm, q 1 = +5  C, x = 3cm, q 2 = -2  C and x = 4 cm, q 3 = -4  C. What is the net force acting on q2? What direction? ans: 620 N to the left What is the charge on two equally charged bodies set 3 cm apart with a force of 63 N ans: 2.5 x 10 -6 C What is meant by ‘electrostatic equilibrium’? p+ = e-, any excess charge on surface

8. An insulator is rubbed on fur or wool, what is the net charge on the insulator? (-) due to an excess of electrons Where is the greatest e- density found on an irregularly shaped conductor? the smallest surface area True or False: Material can be charged by induction? An insulator can transfer a charge through a conductor.

9. Where would the density of an electrostatic charge be the greatest for a hollow conductive sphere? on the surface True or False: Polarization can charge both a conductor and an insulator? True. What is the total net charge of an object in electrostatic equilibrium? zero

10. What is the charge on a proton? +1.6 x 10 -19 C What is the charge on an electron? -1.6 x 10 -19 C What defines an electric field (E)? the force that influences a charged body. E = F elec / q

11. What is the electric field strength of a charge that produces a charge of 5 x 10 -6 C set at 3 cm. ans: 4.99 x 10 7 N/c An electron enters an electric field of 200 N/C. What force is on the electron. ans: 3.2 x 10 -17 N Two charged bodies of +10 C and -20C set 5 m apart. What is the electric force and direction? ans: -7.2 x 10 10 N