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.
Gravitational potential energy = mass × gravity × height
Ep = (4)(9.81)(3)
Energy = 117.72 Joules
= 1.2x10^2 Joules
I only know what number 1. is and its Mechanical Energy.
B. By vibrations in wires or strings
.Answer:
491.4 nm
Explanation:
The distance between central and first maxima is,

And the distance between screen abnd grating is,

Now the angle can be find as,

Now the grating distance is,

Now with m=1 condition will become,

So,

Therefore the wavelength of laser light is 491.4 nm.