What physical effect produces torque in a simple DC motor?

State the ideal torque magnitude for a motor coil.

What is the maximum torque of a motor coil?

A coil has \(N=100\), \(I=0.50\,\mathrm{A}\), \(A=4.0\times10^{-3}\,\mathrm{m^2}\), and \(B=0.20\,\mathrm{T}\). Find maximum torque.

Why does a simple DC motor need a commutator?

What would happen in a simple coil motor without current reversal?

A motor coil has maximum torque \(0.080\,\mathrm{N\,m}\). At \(30^\circ\), what torque does it produce?

How does increasing the number of turns affect motor torque, all else equal?

A motor provides torque \(0.25\,\mathrm{N\,m}\) at angular speed \(120\,\mathrm{rad\,s^{-1}}\). Find mechanical power output.

A motor draws \(2.0\,\mathrm{A}\) from \(12\,\mathrm{V}\). Find electrical input power.

A motor has electrical input \(100\,\mathrm{W}\) and mechanical output \(75\,\mathrm{W}\). Find efficiency.

What is back emf in a spinning DC motor?

Why can a DC motor draw a large current when it first starts?

A motor coil resistance is \(3.0\,\Omega\) and it is connected to \(12\,\mathrm{V}\). Estimate the starting current if back emf is zero.

The same motor has back emf \(9.0\,\mathrm{V}\) while running from \(12\,\mathrm{V}\), with coil resistance \(3.0\,\Omega\). Find the running current.

Why does increasing magnetic field strength increase ideal motor torque?

A motor has output torque \(0.40\,\mathrm{N\,m}\) and output power \(80\,\mathrm{W}\). Find angular speed.

A motor input is \(60\,\mathrm{W}\). It loses \(12\,\mathrm{W}\) as heating and \(6\,\mathrm{W}\) as friction. Find output power and efficiency.

A motor coil has area doubled and current halved. What happens to ideal torque if all else stays fixed?

Explain the energy conversion chain in a real DC motor, including why input power is not all mechanical output power.