Download 1 - Physics Playground

Static, Voltage, and Capacitor Review
Name:_____________
Date:______________
Short Answer and T/F: (3 pts each)
1)
Name two materials that electrons are allowed to move freely on:
2)
If you rub a balloon with a cloth, why does dust become attracted to it?
3)
How does the charge of a proton differ from the charge of an electron?
4)
Explain how an object is charged by polarization: (you may use pictures if needed)
5)
Explain why the leaves of an electroscope repel when a charged source is brought near it?
6)
A charge on a rod is brought near a conductor. Draw an arrow on the sphere that represents the direction the electrons are
repelled.
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7) T/F: An object may become positively charged by electrons transferring between materials
8) T/F: Insulators confine their charges to concentrated areas, this is why a copier works.
Electric Field Calculations:
A)
Find the electric field strength at location A (2meters from
the source) if the sphere has a charge of +2C.
B) Find the force on a +.5C charge that is located at location
A
Electric Fields:
Draw both the charge and the electric field on the following objects: (3pts each)
+ and – plate
Box is -
Plate is +
Voltage: (3pts each)
1) Voltage may be thought as electrical ______________________.
2) The following spheres have charges on them where the “-“ a negative charge.
If a wire where connected between the following spheres state which directions the
electrons will flow:
Between -2C and -9C:_____________
Between -9C and -10C:_____________
-9C
+2C
Between -2C and +7C:____________
Between -10C and +2C:_____________
-10C
+7C
Capacitance:
1) What is the function of a capacitor?
2) Why does a capacitor have a material kept between them?
Calculating capacitance:
1) Find the capacitance of a parallel plate capacitor that has a surface area of .008m2 and a distance between the plates that is
.0003m. Find the capacitance of this capacitor. (5pts) (ans: 2.36 x 10-10 F)
2) If the capacitor above is charged a with a 7V source, find the charge stored in it. (5pts) (ans: 1.65 x 10-9 C)
3) For the same capacitor, find the PE stored in it while charged at 5V. (5pts) (ans: 2.95 x 10-9 J)