TRANS - FORMERS/MISSION OF ELECTRICITY

A device that uses two coils and an iron core to change the voltage across an object or material is called a

• Voltmeter

• Diode

• Transformer

• Generator

The primary coil of a particular transformer has 100 turns in it and the secondary coil has 50 turns.  Such a transformer is

• A step-up transformer

• A step-down transformer

• Either a or b depending on the relative input and output currents

The voltage across a transformer primary coil having 100 turns is 10 V.  What is the voltage across the secondary coil, which has 20 turns?

• 100 V

• 20 V

• 10 V

• 2 V

In a vacuum, electromagnetic waves travel at speeds

• Greater than the speed of light

• Equal to the speed of light

• Less than the speed of light

A transformer works because

• Electricity is induced in a rotating coil

• A changing magnetic field is transferred to a coil via an iron core

• Electricity flows from a primary coil to a secondary coil

• Electricity is transferred to a coil via an iron core

The voltage drop along the cable when electricity is transmitted is found using the formula...

The power loss in the cables when electricity is transmitted is found using the formula...

When electricity is transmitted alternating current (a.c.) is used because

• It minimizes power losses

• The voltage needs to be stepped up and stepped down and transformers only operate on a.c.

• It minimizes hysteresis

• It minimizes heat generated because of resistance in the wires

When electricity is transmitted a very high voltage is used because

• It minimizes power losses

• The voltage needs to be stepped up and stepped down and transformers only operate on a.c.

• It minimizes hysteresis

• It minimizes heat generated because of resistance in the wires

Transformers are made using soft iron cores because

• It minimizes power losses

• The voltage needs to be stepped up and stepped down and transformers only operate on a.c.

• It minimizes hysteresis

• It minimizes heat generated because of resistance in the wires