Question

Four identical metallic objects carry the following charges: +1.82, +6.98, -4.95, and -9.10C. The objects are brought simultaneously into contact, so that each touches the others. Then they are separated. (a) What is the final charge on each object? (b) How many electrons (or protons) make up the final charge on each object?

Answer 1

When two or more metal objects are touched and separated then total charge on each object is equally distributed. Here since four metallic objects are brought simultaneously brought into contact, So after separation charge on each object will be:

Q = (Q1 + Q2 + Q3 + Q4)/4

Q = (1.82 + 6.98 - 4.95 - 9.10)/4 = -1.3125 C

In three significant figures

final charge on each object = -1.31 C

(many time sign is not shown on site, so if your each charge has value in C, then final answer will be: -1.31 C)

Part B.

Number of electrons in a charged object is given by:

Q = n*e

n = Q/e

e = charge on electron = -1.6*10^-19 C

Q = charge on each object = -1.31 C

n = -1.31/(-1.6*10^-19) = 8.20*10^18 electrons

Again if your given charge have sign than n = -1.31*10^-6/(-1.6*10^-19) = 8.20*10^12 electrons

Let me know if you've any query.