Element Symbol
Protons
Neutrons
Electrons Atomic # Atomic
Mass
7
lon? If yes,
charge
No
Nitrogen
7
N
Sodium
11
23
Yes, +1
Na
Gold
au
79
197
No
79
22
79
118
25
20
20
19
19
Titanium
Ti
Potassium
k
Mercury
Hg
Hydrogen H
19
41
80
76
201
0
1
lodine
I
127
Yes, -3
Uranium
92
92
238
Calcium
Ca
20
20
20
20
41
Yes, +2
Iron
Fe
30
Yes, +3
26
26
26

Na food processing facility, a spherical container of inner radius r1 5 40 cm, outer radius r2 5 41 cm, and ther- mal conductivity k 5 1.5 w/m · k is used to store hot water and to keep it at 100°c at all times. to accomplish this, the outer surface of the container is wrapped with a 800-w electric strip heater and then insulated. the temperature of the inner surface of the container is observed to be nearly 120°c at all times. as- suming 10 percent of the heat generated in the heater is lost through the insulation, (a) express the differential equation and the boundary conditions for steady one-dimensional heat conduction through the container, (b) obtain a relation for the variation of temperature in the container material by solving the differential equation, and (c) evaluate the outer surface tempera- ture of the container. also determine how much water at 100°c this tank can supply steadily if the cold water enters at 20°c.

Atotal charge of –6.50 µc is uniformly distributed within a sphere that has a radius of 0.150 m. what is the magnitude and direction of the electric field at 0.300 m from the surface of the sphere? a) 2.89 × 105 n/c, radially inward b) 6.49 × 105 n/c, radially outward c) 4.69 × 105 n/c, radially inward d) 9.38 × 105 n/c, radially outward e) 1.30 × 106 n/c, radially inward

Astudent wears sunglasses to her read a book more easily which wave interaction occurs as light passes from the air into the plastic lenses? a polarization b.refraction c.diffraction d. interference