7. Referring to the figure 2, calculate the image distance if a point object is situated in the medium of refractive index ni at a distance of
(a) 50 cm and
(b) 4 cm
from the spherical surface of radius of curvature 5 cm if ni and n2 are
1.0 and 1.52 respectively.​

The radiation of the fire causes the saucepan to heat up. the conduction of the saucepan then to distribute the heat over the saucepan and to give heat to the water. the convection of the water distributing the heat within the water, till all the water is boiling

An atom's smaller negative particles are at a distance from the central positive particles, so the negative particles are easier to move.