The generation of a magnetic field by an electric current is _electromagnetism_.
Answer:
B train!
Explanation:
A train travelled at 40 km/hr. (120/3)
B train traveled at 45 km/hr (180/4)
2.89watts.
<h3>What is meant by sound intensity?</h3>
- The average rate at which sound energy moves across a unit area normal to a given direction is used to determine a sound's intensity. This rate is generally stated in ergs per second per square centimeter.
- Decibels are the units used to measure sound intensity, often known as sound power or sound pressure. The decibel (dB) unit is named after Alexander Graham Bell, who also created the audiometer and the telephone. An audiometer is a tool to gauge a person's hearing capacity for various noises.
- Our ability to measure the flow of sound energy as a time-averaged vector quantity makes sound intensity measuring an effective method. We can identify sound sources and tell direct sound from reverberant sound in a room using the characteristics of sound intensity.
How much power is radiated as a sound from a band whose intensity is 1.6x10-3 w/m2 at a distance of 12m:
Formula: 
I=1.6x10-3 w/m2
r=12m




To learn more about sound intensity, refer to:
brainly.com/question/17062836
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It’s C I hope it helps you
Answer: Some conversions from one system of units to another need to be exact, without increasing or decreasing the precision of the first measurement. This is sometimes called soft conversion. It does not involve changing the physical configuration of the item being measured.
Explanation: