6d: Electromagnetic Induction

What must a wire do to induce a voltage?

• Cut a magnetic field
• Interact with a magetic field
• Touch a magnetic field
• Be connected to a battery

What happens when a magnetic field is cut by a wire?

• A force is produced in the wire
• A voltage is induced in the magnetic field
• A voltage is induced in the wire
• A current is induced in the wire

What does a step-up transformer do?

• Increase voltage, decrease current
• Increase voltage, decrease current, increase power
• decrease voltage, increase current
• decrease voltage, increase current, decrease power

What does a step-down transformer do?

• Increase voltage, decrease current
• Increase voltage, decrease current, increase power
• decrease voltage, increase current
• decrease voltage, increase current, decrease power

Why do we use step-up transformers in the National Grid?

• To reduce energy wasted (in the National Grid)
• To change the direction of the current
• To improve safety (in homes)
• To move electricity uphill

Why do we use step-down transformers in the National Grid?

• To reduce energy wasted (in the National Grid)
• To change the direction of the current
• To improve safety (in homes)
• To move electricity downhill

A transformer needs what kind of current to work?

• Alternating / AC
• Direct / DC

You can increase the voltage induced by…

• increasing the speed of the movement
• increasing the number of turns of wire on the coil
• increasing the strength of the magnetic field
• Increasing the input voltage
• Increasing the sharpness of the wires

What happens in the primary coil of a transformer?

• An alternating current produces a changing magnetic field.
• The magnetic field is strengthened.
• The changing magnetic field is cut, inducing an alternating voltage
• The voltage is stepped up
• The voltage is stepped down

What happens in the iron core inside a transformer?

• An alternating current produces a changing magnetic field.
• The magnetic field is strengthened.
• The changing magnetic field is cut, inducing an alternating voltage
• The voltage is stepped up
• The voltage is stepped down