the answer is J. 3,900,000 got it right on the test
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.
Answer:
He is testing for voltage drop (voltage drop test)
Explanation:
Connecting the red lead of a voltmeter to the B+ output to an ac generator and black lead to a battery +ve terminal measures the voltage drop in the circuit when the engine is turned ON and all electrical accessories too.
with this he knows if the alternator is charging the battery.
The change in pitch of a train's horn as it passes while you are standing still can be explained by the Doppler effect. The correct option among all the options given in the question is option "A". When the sound source from the horn of the train comes closer, the sound seems to come closer each time a sound wave gets emitted. So it comes closer to us in a bunched form. The reverse happens when the train has just passed with each emitted sound going further and further away. The frequency of the sound seems to get lower as the train moves further away.
