Question

I worked out the problem several times and keep getting the wrong answer I got .00001289604743 for my first try and apparently it's wrong :/

Birds resting on high-voltage power lines are
a common sight. A certain copper power line
carries a current of 50.6 A, and its resistance
per unit length is 8.26 × 10−5 Ω/m.
If a bird is standing on this line with its feet
7.9 cm apart, what is the potential difference
across the bird’s feet?
Answer in units of V

Answer 1

@Arctangent

Answer 2

I did R=(8.26 x 10^-5) 7.9/50.6

Answer 3

@ankit042

Answer 4

Resistance is given per unit length. Now you have to find resistance for 7.9 cm
so R = (8.26 x 10^-5)*7.9/100
then use V=IR

Answer 5

So .00033018524

Answer 6

Can I ask my second question now?

Answer 7

A potential difference of 12 V is found to
produce a current of 0.3 A in a wire of length
3.4 m with a uniform radius of 0.34 cm.
What is the resistance of the wire?
Answer in units of Ω
What is the resistivity of the wire?
Answer in units of Ω · cm

Answer 8

I got 40 for the first one and it is right I tried applying the answer to the second part of the question and its coming out wrong I did 40=resistivity sign(3.4/.3631681108)

Answer 9

Yes 40 is correct!
now this is same as we did the last question. R= (resistivity)*length/Area
now you have to calculate the area of circle.
Make sure you convert all the distance units to cm. Because we have to answer in ohm cm

Answer 10

so resistivity x .034
then divide by .3631681108

Answer 11

I think so!

Answer 12

but how would I write that since the resistivity isnt a number I wouldnt get a solution to then divide by .3631681108

Answer 13

sorry it will not be .034. You have to convert meters to cm
You know how to convert m to cm?
so final answer 40*.3631681108/3.4*100

Answer 14

Oh okay so ressitivity is .0427256601

Answer 15

Thanks so much!!

Answer 16

np :)
You knew the concept...just make sure you put the right units. sometimes in physics you have to convert

Answer 17

How many electrons pass a given point in the
circuit in 19 min? The fundamental charge is
1.602 × 10−19 C.

The current in a resistor decreases by 2.36 A
when the voltage applied across the resistor
decreases from 17.7 V to 6.44 V .
Find the resistance of the resistor.
Answer in units of Ω

I'm confused on these two, what equations do I use ?

Answer 18

@ankit042

Answer 19

u have any idea how to proceed?

Answer 20

Well I tried to determine this : (1.602 × 10^−19 C) (1.6 x 10^-19) then I divided that by 19

Answer 21

the secnod one I didn't know how to approach it since there are to V's

Answer 22

so it talks about change in voltage and change in current.
Now as resistance remains constant you can use delta(v) = delta(I)*R

Answer 23

This is for the second right?

Answer 24

right

Answer 25

So is it delta 17.7 x delta 6.44= delta 2.36 x R
or is this completely wrong?

Answer 26

delta(v) = 6.44-17.7
delta(I) = -2.36

Answer 27

So R=4.771186441

Answer 28

Now for the first one is there an equation for that?

Answer 29

Do we know thr current passing in the circuit?

Answer 30

I don't think so unless thats the same as the fundamental charge

Answer 31

How many electrons pass a given point in the
circuit in 19 min? The fundamental charge is
1.602 × 10−19 C.

Answer 32

Do I divide 1.602 × 10^−19 C by 19