Answer with Explanation:
We are given that
Magnetic field,B=

Length of wire,l=15 m
Current,I=19 A
a.We have to find the magnitude of magnetic force and direction of magnetic force.
Magnetic force,F=
Using the formula


Direction=

15 degree above the horizontal in the northward direction.
Answer:
The sound intensity of train is 1000 times greater than that of the library.
Explanation:
We have expression for sound intensity level,

A train whistle has a sound intensity level of 70 dB
We have

A library has a sound intensity level of about 40 dB
We also have

Dividing both equations

The sound intensity of train is 1000 times greater than that of the library.
ripples on the surface of water.
vibrations in a guitar string.
a Mexican wave in a sports stadium.
electromagnetic waves – eg light waves, microwaves, radio waves.
seismic S-waves.
The dye in between the two pieces of glass in the filter absorbs all the other colors in the white light except the red, and the red is the only light left to come out the other side. That's why the filter usually looks kind of red. It's also a big part of the reason why we call it a "red filter".