We are here with you hands in hands to facilitate your learning & don't appreciate the idea of copying or replicating solutions. Read More>>

www.vustudents.ning.com

 www.bit.ly/vucodes + Link For Assignments, GDBs & Online Quizzes Solution www.bit.ly/papersvu + Link For Past Papers, Solved MCQs, Short Notes & More

Dear Students! Share your Assignments / GDBs / Quizzes files as you receive in your LMS, So it can be discussed/solved timely. Add Discussion

# PHY101 Assignment 3: (Spring 2013)

Spring%202013_PHY101_3.docx

Physics (PHY101)

VU of Pakistan
Assignment 3: (Spring 2013)
PHYSICS (PHY101)
TOTAL MARKS: 30
Due Date: 01/07/2013
DON’T MISS THESE Important instructions:
• To solve this assignment, you should have good command over first 28 lectures.
• Upload assignments (Microsoft word) properly through LMS, (No Assignment will be
accepted through email).
• All students are directed to use the font and style of text as is used in this document.
• Don’t use colorful back grounds in your solution files.
• Write to the point and avoid from unnecessary explanation. Don’t copy/paste from
internet or any other source.
• Use Math Type or Equation Editor etc for mathematical symbols.
• This is not a group assignment, it is an individual assignment so be careful and avoid
copying others’ work. If some assignment is found to be copy of some other, both will be
awarded zero marks. It also suggests you to keep your assignment safe from others. No
excuse will be accepted by anyone if found to be copying or letting others copy.
Don’t wait for the last date to submit your assignment.
Question # 1
Two charged spheres are held a distance, r, apart. One sphere has a charge of +4μC, and the other sphere has a
charge of +8μC. Compare the force of the +4μC sphere on the +8μC sphere with the force of the +8μC sphere
on the +4μC sphere. (Note: Answer should not be greater than a one line). Marks = 5
Question # 2
I. When do you wipe a compact disc with a clean cloth, why does the CD begin to attract
dust again?
II. The constant, K, in Coulomb’s equation is much larger than the constant, G, in the
universal gravitation equation. Of what significance is this? Marks = 5 (2+3)
Question # 3
I. A positive charge of 5.0×10-7 C is located in a field of 30 N/C directed toward the south.
What is the force acting on the charge?
II. How is the direction of an electric field defined?
III. Why can birds perch on high voltage lines without being injured? Marks = 9 (5+2+2)
Physics (PHY101) VU of Pakistan
Question # 4
Jamil and Salma are standing on an insulating platform and holding hands when they are given a
charge, as in Figure Jamil is larger than Salma. Who has the larger amount of charge, or do they
both have the same amount? Marks = 4
Question # 5
The circuit above shows two 1.5V batteries connected so that the current flows through the three
light bulbs which have 10 Ω, 5Ω and 15 Ω resistances as shown. In this circuit:
a. Electrons flow clockwise through the circuit.
b. The flow of current is greatest, through the 5 Ω resistor.
c. The light bulbs have different voltages over them.
d. The flow of current is least, through the 5 Ω resistor.
e. The batteries and light bulbs are connected in parallels.
Note: Explain the reason of your above selected choice as well.
Marks = 7(3+4)
<Wish you good luck>>>>>>>>>>>>

+ How to Join Subject Study Groups & Get Helping Material?

+ How to become Top Reputation, Angels, Intellectual, Featured Members & Moderators?

+ VU Students Reserves The Right to Delete Your Profile, If?

Views: 2077

.

+ http://bit.ly/vucodes (Link for Assignments, GDBs & Online Quizzes Solution)

+ http://bit.ly/papersvu (Link for Past Papers, Solved MCQs, Short Notes & More)

Attachments:

### Replies to This Discussion

for question no.3 part1 use this equation to do calculation   E=F/q

where E vector is electrical field(N/M) F vector is electric force in newtons and q is charge in coulombs

if any1 got an alternative idea or think this is not right feel free to rectify but be quick

Solution plzZZ

Why can birds perch on high voltage lines without being injured?

1. ## Birds on a Wire

• Electrocution is injury or death that occurs because of electrical shock. If birds sitting on a wire are not getting electrocuted, this means they are not getting shocked by electricity. Essentially, this means that the electricity is able to pass through the birds without damaging them. Electricity works via electrons flowing through conductors. If a bird is able to sit on an electrical wire, it means that the bird is not a good conductor of electricity.

## A Bird Is Not a Good Conductor of Electricty

• Birds are able to sit on electrical power lines because the electrical current essentially ignores the bird's presence and continues to travel through the wire. A bird's body is not a good conductor of electricity. Electricity, similar to water, flows using the least amount of resistance possible. In electrical power lines, electricity flows along copper wires. Copper is an excellent conductor of electricity in that it allows electricity to flow easily along its surface. A bird, on the other hand, is made of cells and tissues. These cells and tissues do not provide the electricity in the wire with an easier route to travel than the one it is already on. Because a bird's body is not a good conductor of electricity, the electricity essentially ignores the bird on the wire and continues to travel along the copper wiring to its destination.

## Touching the Wire and the Ground

• While birds may sit on the wires of power lines and essentially be safe, they will not be so lucky if they happen to touch the ground while touching a power line. This is because the ground, or a transformer, or a place where the electricity is stored for use, is a place where there is essentially no voltage. Electricity travels from a place of high voltage to low voltage, just as water travels from high elevation to low elevation. A bird, or any living thing, that touches a wire (where electricity is moving from high voltage to low voltage) and also touches the ground (a place with no voltage) creates a path that allows the electricity to travel through that body and into the place with no voltage. When electricity travels through a body in this fashion, electrocution takes place, and the bird can die.

The power line is at a high voltage potential, but it is just that - a potential. The bird can perch on the line and come to the same potential voltage as the line with no shock. If there is no complete path from that potential to a higher or lower potential or to ground, no current will flow and the bird will not experience a shock. If you could jump up and grab that power line (without touching anything that would provide a path to ground) you could do the same thing that the bird is doing. Voltage does not hurt you absent current flow.

If the potential is high then a small segment of the line (the distance between the feet of the birds) will provide some potential difference. This will mean a current will flow through the bird. Is that correct? Although if we allow V small and R large than V=IR => small I. Is your argument that I in this case is too small to cause the bird harm. Someone dangling on the voltage lines will not cause harm for the same reason although provided their arms are not too widely spaced? Otherwise the potential difference will be larger however R for a human is smaller than a bird.

n@z gud keep it up & thanks for sharing

Attention Students: You don’t need to go any other site for this assignment/GDB/Online Quiz solution, Because All discussed data of our members in this discussion are going from here to other sites. You can judge this at other sites yourself. So don’t waste your precious time with different links.

M.Tariq Malik u r well ComE :) u also RockinG :)

N@z, You're very best

any ideas about question no 5???????

## Latest Activity

Sukaina and Soldier are now friends
18 minutes ago
Noman Ijaz liked + ! ! ! ❣ Sanam ❣ !+'s profile
1 hour ago
Soldier liked Sukaina's profile
1 hour ago
Bilal joined +M.Tariq Malik's group

### MTH001 Elementary Mathematics

2 hours ago
Preety Girl is now a member of Virtual University of Pakistan
2 hours ago
Mani Siddiqui BS VIII liked + ! ! ! ❣ Sanam ❣ !+'s profile
3 hours ago
maheen mahan joined +M.Tariq Malik's group

### CS502 Fundamentals of Algorithms

7 hours ago
maheen mahan added a discussion to the group CS610 Computer Network

### cs610 gdb idea solution spring2020

8 hours ago
8 hours ago
8 hours ago
"hi i am new here! any one from sailkot?"
9 hours ago
+ ! ! ! ! !Marshmallow updated their profile
16 hours ago

1

2

3