Microphone — Questions and answers
Read the full story
What did Dr. Evelyn Reed say was the key to making sound waves create a strong electrical current?
Choices
- Using a feather to touch the wires.
- Making the electrical current flow in a roaring river.
- Harnessing variable electrical resistance. ✓
- Stopping the sound waves from vibrating too much.
Answer: Harnessing variable electrical resistance.
From page 2
Why was Alexander Graham Bell's 'liquid transmitter' not good for everyone to use?
Choices
- It made the sound too quiet to hear.
- The special liquid was too hard to find.
- The liquid was dangerous and would break the parts inside. ✓
- It only worked when the water was very cold.
Answer: The liquid was dangerous and would break the parts inside.
From page 3
What special thing did David Edward Hughes discover about carbon?
Choices
- It could light up a room in the dark.
- It could change how much electricity flows when sound pushes on it. ✓
- It was the lightest material on Earth.
- It made a loud buzzing sound when electricity went through it.
Answer: It could change how much electricity flows when sound pushes on it.
From page 4
What was an important feature of Emile Berliner's carbon transmitter design?
Choices
- It used a loose, wobbly metal diaphragm.
- It had a strong, solid contact between a metal diaphragm and a carbon button. ✓
- It used a special type of liquid to help with the sound.
- It was made completely out of wood.
Answer: It had a strong, solid contact between a metal diaphragm and a carbon button.
From page 5
What was Thomas Edison's big improvement to the carbon transmitter?
Choices
- He made it much smaller to fit in a pocket.
- He used packed carbon granules instead of one big piece of carbon. ✓
- He added more colorful wires to the design.
- He made it so it could also play music.
Answer: He used packed carbon granules instead of one big piece of carbon.
From page 6
How does Edison's carbon microphone make more electricity flow when someone speaks into it?
Choices
- The sound makes the wires light up.
- The sound makes the carbon granules press together, allowing more electricity to pass. ✓
- The sound waves make the microphone get hotter.
- The sound waves magically create new electricity.
Answer: The sound makes the carbon granules press together, allowing more electricity to pass.
From page 7
What big change did Edison's carbon microphone bring to telephone calls?
Choices
- It made telephones much cheaper to buy.
- It made telephone calls clear and loud over long distances. ✓
- It made telephones work with colorful lights.
- It allowed telephones to send pictures as well as sound.
Answer: It made telephone calls clear and loud over long distances.
From page 8