Back EMF Demonstration

The video tutorial explains the concept of back EMF in electric motors, highlighting its role in reducing current when the motor is rotating. It discusses the absence of back EMF during motor startup, leading to higher current. A practical example using a miter saw illustrates how back EMF affects circuit load and light brightness, emphasizing the increased load and decreased current available for other devices when the motor is starting up.

What is the effect of back EMF on the current in an electric motor?

• It reverses the current direction.

• It reduces the current.

• It has no effect on the current.

• It increases the current.

When is back EMF absent in an electric motor?

• When the motor is rotating at high speed.

• When the motor is overloaded.

• When the motor is not rotating.

• When the motor is rotating at a constant speed.

Why is the current larger when an electric motor is starting up?

• Because the motor is under no load.

• Because the motor is overloaded.

• Because there is no back EMF initially.

• Because the motor is at a constant speed.

What happens to the light when an electric motor starts up?

• The light becomes brighter.

• The light dims.

• The light flickers.

• The light turns off.

How does back EMF affect the circuit when an electric motor is starting?

• It causes more load on the circuit.

• It decreases the load on the circuit.

• It increases the available current for other devices.

• It stabilizes the circuit voltage.