Answer:
F1 = K Q1 Q2 / R1^2
F2 = K Q1 / 2 * Q2 / (2 R1)^2
F2 / F1 = 1/2 / 4 = 1/8
The new force is 5N (1/2 due to charge and 1/4 due to distance)
A soft metal core made into a magnet by the passage of electric current through a coil surrounding it.
Answer:

Explanation:
The Hi line of the Balmer series is emitted in the transition from n = 3 to n = 2 i.e.
and 
The wavelength of Hi line of the Balmer series is given by :




So, the wavelength for this line is 550 nm. Hence, this is the required solution.
Answer:
the yield of product is YP=46.835 % and the concentration of solids is
Cs = 27.33%
Explanation:
Assuming that all the solids and fats remains in the milk after the evaporation, then the mass of product mP will be
Mass of fat in 100 kg of milk = 100 kg* 0.037 = mP* 0.079
mP = 100 kg* 0.037/0.079 = 46.835 kg
then the yield YP of the product is
YP= mP / 100 kg = 46.835 kg / 100 kg = 46.835 %
YP= 46.835 %
the concentration of solids Cs is
Mass of solids in 100 kg of milk = 100 kg* 0.128 = 46.835 kg * Cs
Cs = 100 kg* 0.128 / 46.835 kg = 0.2733 = 27.33%
Cs = 27.33%