Torque on Charges in an Electric Field

[Mitchtwitchita]

Homework Statement

Two small plastic spheres, one charged to 17 nC and the other to -17 nC, are connected by a 25-mm long insulating rod. Suppose this dipole is placed in a uniform electric field with strength 7.4 x 10^5 N/C. What is the maximum possible torque on the dipole?

Homework Equations

t = qEL

The Attempt at a Solution

t = qEL
=(17 x 10^-9 C)(7.4 x 10^5 N/C)(2.5 x 10^-2 m)
=3.15 x 10 ^-4 J
This can't be right. Is torque measured in Joules? Can somebody please help me out with this problem?

 

[rock.freak667]

Your unit is Nm, which is right for torque, not the equivalent J for energy.

 

[Mitchtwitchita]

How about the solution?

 

[rock.freak667]

Looks correct to me.