Answer:
B'=1.935 T
Explanation:
Given that
magnetic field ,B= 0.645 T
We know that magnetic filed in the solenoid is given as

I=Current
n=Number of turn per unit length
μ0 =magnetic permeability
Now when the current increased by 3 factors
I'=3 I
Then the magnetic filed


B'=3 B
That is why
B' = 3 x 0.645 T
B'=1.935 T
Therefore the new magnetic filed will be 1.935 T.
Answer:
25 mm = 0 deg C
200 mm = 100 deg C
200 - 25 = 175 = change in thread per 100 deg C
95 - 25 = 70 mm - change in thread from 0 deg C
70 / 175 * 100 = 40 deg C final temperature at 95 mm
Answer:
Frequency, 
Explanation:
We have,
Speed of radio waves is 
Wavelength of radio waves is 
It is required to find the frequency of the radio waves. The speed of a wave is given by :

So, the frequency of the radio wave is
.
Answer:
State A = piece of metal; State B = air
Explanation:
For the three main states of matter here's how it breaks down.
Solid - Cannot be compressed and retains its shape
Liquid - Cannot be compressed and does not retain its shape
Gas - Compressible and does not retain its shape.
Knowing this State A has to be solid. Only one of the options has A as a solid, so that's the answer. Worth knowing state B is a gas though, only one compressible, just like solid is the only one that retains its shape.