Question

working models for 9th class

Answer 1

how to make a microphone:

take a funnel.
make four holes opposite to each other and parallel
fix two pencil leads.
they are in paralell
connect the wires to the pencil leads.
attach to a battery and speaker.
place a paper cup on the top of pencil leads.
speak loud in the cup .
the voice will hear in the speaker.

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Answer 2

"Working model"
'A vertical wind turbine power generator!'
Materials required:
1) DC motor generator/ Dynamo
2) wooden squeers
3) paper/transparent plastic sheet
4) cylindrical container
procedure:
1 make a propeller by joining all 6 wooden squeers.
2 take a sheet of  transparent plastic sheet, bent it and join it vertically with the squeers.
3 now join the dynamo with your propeller
4 when joining all parts of the turbine is done put the motor in side the container and propeller facing outwards.