Answer:
True there is the permanent magnet and the electromagnet.
Answer:
c) wafers of crystalline silicon treated with metals that absorb solar radiation and generate electricity
Explanation:
Photovoltaic solar cells are used in solar panels. Most of the photovoltaic cells are made from crystalline silicon.
It has a property using which it converts the light (solar radiation) falling on it to electrical energy. This process occurs due to the photovoltaic effect.
It is a way generating energy without consuming fossil fuels. Thus it reduces the carbon emission and thus plays a major role in environment protection.
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The time it takes "to complete one cycle" is a perfect definition for <em>period</em>.
So the <em>2 sec</em> that you measured is the swing's period.
Frequency is just 1/period (the 'reciprocal' of the period).
For this swing, the frequency is 1/(2sec) = 0.5 per second = <em>0.5 Hz</em>.
( "Hertz" means "per second")
the upside down image means an inverted image and for an inverted image, magnification is negative
so the answer is -m