EMF induced in a rotating rod having mass

AI Thread Summary
The discussion focuses on calculating the induced electromotive force (emf) and torque in a rotating rod. The user initially seeks guidance on finding the current and relates emf to resistance using the equation emf = IR. It is clarified that for the rod to rotate at constant angular velocity, the net torque must be zero, meaning the torque due to gravity is balanced by the torque from the induced current. A free body diagram is suggested as a useful tool for visualizing the forces and torques involved. The user acknowledges the need to differentiate between force and torque in their calculations.
Physics lover
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Homework Statement
The question is put in Attempt at a solution.
Relevant Equations
emf induced in a rotating rod = Bwr##^2##/2
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I first calculated induced emf and then calculated torque about O.But what will i do further.I think i need to find current and then fidn emf=IR.
Help please.
 
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Please show your work. It is supposed to go in "Attempt at a solution" but now it has to go in separate post. Ask yourself, "What does it mean to have the rod rotate at constant angular velocity?"
 
kuruman said:
Please show your work. It is supposed to go in "Attempt at a solution" but now it has to go in separate post. Ask yourself, "What does it mean to have the rod rotate at constant angular velocity?"
it means that there is not external torque that is torque of mg is balanced by torque of induced current.
 
kuruman said:
Please show your work. It is supposed to go in "Attempt at a solution" but now it has to go in separate post. Ask yourself, "What does it mean to have the rod rotate at constant angular velocity?"
i have shown how much i have proceeded far.Now i cannot do it further.
 
Physics lover said:
It means that there is not external torque that is torque of mg is balanced by torque of induced current.
And where is the equation that says that? Parenthetically, there are two external torques. What you meant to say is that there is no net torque. Right? This is a torque balance problem. What does one normally do with such problems? Hint: Free body diagram.
 
kuruman said:
And where is the equation that says that? Parenthetically, there are two external torques. What you meant to say is that there is no net torque. Right? This is a torque balance problem. What does one normally do with such problems? Hint: Free body diagram.
ok i think i got that.The emf to be find out will have its own torque =IBL which will balance the torque of mg and induced current.Am i right?
 
Physics lover said:
ok i think i got that.The emf to be find out will have its own torque =IBL which will balance the torque of mg and induced current.Am i right?
You are right except that IBL is a force, not a torque.
 
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