# physics

posted by .

An 8m long copper wire with a cross-sectional area of 1.0 x 10^-4 m^2, in the sshape of square loop, is connected to a .10-V battery. If the loop is placed in a uniform magnetic field of magnitude .4T, what is the maximum torque that can act on it? The resistivity of copper is 1.7x10^-8 omega*m (answer: 120 N*m) I can't seem to get the answer. Any help is appreciated!

work:
I=V/R=(.10V)/((1.7x10^-8)/8m))
torque=BIA=(.4T)(I)(10^-4 m^2)

• physics -

You have not used the wire resistance R in the Ohm's law equation; you used resistivity, which must be multiplied bu L/A*, where A* is the cross sectional area of the wire (1.0 x 10^-4 m^2) and L is its total length (8 m). The area A that should go into your second equation is the coil area, (L/4)^2 = 4 m^2, since is it s square.

## Similar Questions

1. ### Physics

Would someone check this please? A circular loop of wire of radius 0.10 m and of resistance 2.0 ~ 10−3 ƒ¶ is in a region where there is a uniform magnetic field B. The field is at 30‹ to the normal to the plane of the
2. ### Physics

A copper wire is 7.00 m long and has a cross-sectional area of 1.00 10-4 m2. This wire forms a one turn loop in the shape of a square and is then connected to a battery that applies a potential difference of 0.200 V. If the loop is …
3. ### PHYSICS

A circular loop of flexible iron wire has an initial circumference of 168cm , but its circumference is decreasing at a constant rate of 15.0cm/s due to a tangential pull on the wire. The loop is in a constant uniform magnetic field …
4. ### physics

A circular wire loop has radius R = 0.327 m and carries current i = 0.291 A. The loop is placed in the xy-plane in a uniform magnetic field pointing in the negative z direction with magnitude 3.83 T, as shown in the figure. a) Determine …
5. ### physics

A flat loop of wire consisting of a single turn of cross-sectional area 8.10 cm2 is perpendicular to a magnetic field that increases uniformly in magnitude from 0.500 T to 1.90 T in 0.95 s. What is the resulting induced current if …
6. ### PHYSICS

A flat loop of wire consisting of a single turn of cross-sectional area 8.10 cm2 is perpendicular to a magnetic field that increases uniformly in magnitude from 0.500 T to 1.90 T in 0.95 s. What is the resulting induced current if …
7. ### physics

A square loop of wire of side 2.8 cm carries 3.0 A of current. A uniform magnetic field of magnitude 0.67 T makes an angle of 43° with the plane of the loop. (a) What is the magnitude of the torque on the loop?
8. ### Physics

A square loop of wire of side 3.0 cm carries 3.0 A of current. A uniform magnetic field of magnitude 0.67 T makes an angle of 37degree with the plane of the loop. What is the magnitude of the torque on the loop?
9. ### physics

a rectangular loop with a=6.0 cm, and b=4.0 cm, moving with a velocity v=8.0 cm/s into an area where the magnetic field is uniform, pointing into the page, and whose magnitude is B= 440 mT. a) What is in volts the induced emf in the …
10. ### physics

A loop of surface area s1=10cm^2 placed ina uniform magnetic field Bof magnitude B1=8×10^-2T, has its plane perpendicular to the field lines . A second loop of area s2=15cm^2 is placed in another uniform field B2 of magnitude B2=0.1T …

More Similar Questions