Answer:
Vb = k Q / r r <R
Vb = k q / R³ (R² - r²) r >R
Explanation:
The electic potential is defined by
ΔV = - ∫ E .ds
We calculate the potential in the line of the electric pipe, therefore the scalar product reduces the algebraic product
VB - VA = - ∫ E dr
Let's substitute every equation they give us and we find out
r> R
Va = - ∫ (k Q / r²) dr
-Va = - k Q (- 1 / r)
We evaluate with it Va = 0 for r = infinity
Vb = k Q / r r <R
We perform the calculation of the power with the expression of the electric field that they give us
Vb = - int (kQ / R3 r) dr
We integrate and evaluate from the starting point r = R to the final point r <R
Vb = ∫kq / R³ r dr
Vb = k q / R³ (R² - r²)
This is the electric field in the whole space, the places of interest are r = 0, r = R and r = infinity
We can define power as the rate of doing work, it is the work done in unit time. The SI unit of power is Watt (W) which is joules per second (J/s). Sometimes the power of motor vehicles and other machines are given in terms of Horsepower (hp) which is approximately equal to 745.7 watts.
Power is the rate at which a force is applied to an object for example.current wire
Answer:
1:2
Explanation:
It is given that,
Initial RMS AC voltage is 100 V and final RMS AC voltage is 200 V.
We need to find the ratio of the number of turns in the primary to the secondary for step up transformer.
For a transformer, 
So,

So, the ratio of the number of turns in the primary to the secondary is 1:2.
Answer:
The wavelength of the visible line in the hydrogen spectrum is 434 nm.
Explanation:
It is given that, the wavelength of the visible line in the hydrogen spectrum that corresponds to n₂ = 5 in the Balmer equation.
For Balmer series, the wave number is given by :

R is the Rydberg's constant
For Balmer series, n₁ = 2. So,


or

So, the wavelength of the visible line in the hydrogen spectrum is 434 nm. Hence, this is the required solution.
Missing information
Consider a superconducting MRI magnet for which the magnet field decreases from 8.0 T to nearly 0 in 20 s
Answer:
0.152 mV
Explanation:
Change in magnetic field, dB=8-0=8 T
Time interval, dt=20 s
Diameter of ring= 2.2cm hence radius is 1.1 cm equivalent to 0.011
where n is the number of terms and for this question n=1 and A is area which is given by
hence
and substituting the values
Therefore, induced emf is 0.152 mV