Qualification > Sciences

Physics help

(1/3) > >>

Saladin:
Can someone please tell me how to solve this question:


The question in in the Edexcel AS student book page 126

In a resistance experiment, a gold ring was connected into a circuit as a resistor. The connection touched diametrically opposite points on the circular ring. Its diameter is 2 cm, and the metal's cross section is 3 mm by 0.5 mm. The voltemeter connected accross the ring measured 8.3 mV, whislt the current through it measured 18 A.

a) Calculate the resistivity of gold
b) Describe a practical difficulty in this experiment

astarmathsandphysics:
Gimme half am hour to get up

loggerhead:
heres my effort, not to sure if its right.

R = P * L / A

first we need to work out R, L and A

R = V / I
R = 0.0083 /18
R = 0.000461

L = half circumference
L = 1/2 * pi * 0.02
L = 0.0314

A = 2 * cross sectional area
A = 2 * 0.003 * 0.0005
A = 0.000003

therefore 0.000461 = P * 0.0314 / 0.000003
P = 0.000461 * 0.000003 / 0.0314
P = 4.4 * 10^-8 ohm m

hope thats right.

not to sure about part b) possibly to do with such small measurements that theres a high %age error, or that the cross sectional area is inconstant

astarmathsandphysics:
It might be difficult to get contacts on exactly opposite sides of the ring. Loggerhead I think your answer is cirrect.

Saladin:
I did not understand how u calculated L though....

Navigation

[0] Message Index

[#] Next page