Answer:
The magnetic field is
T
Explanation:
Given:
Velocity of electron 
Electric field 
The force on electron in magnetic field is given by,
......(1)
The force on electron in electric field is given by,
......(2)
Compare both equation,

Here 



T
Therefore, the magnetic field is
T
Answer:
c. 0.25km
Explanation:
v=f x wavelength
3000 = 12 x wavelength
wavelength = 3000/12 = 250m
250m to km
To convert m to km, we divide by 1000
250/1000 =0.25km
wavelength = 0.25km
The explanation for the following answer is explained below.
Explanation:
The sun is at an average distance of about 93,000,000 miles(150 million kilometers) away from the earth.It is so far away that light from the Sun,travelling at a speed of 186,000 miles (300,000 kilometers) per second, takes about 8 minutes to reach the earth.Earth does not travel around the Sun in a perfect circle.Instead its orbit is elliptical,like a stretched circle,with the sun just off the center of the orbit. At its closest,the Sun is 91.4 million miles (147.1 million kilometers ) away us.At its farthest ,the Sun is 94.5 million miles (152.1 million km) away.The Earth is closest to the Sun during winter in the northern hemisphere
A) the sound waves were pushed closer together