Question

 

1). A total charge of 3.30 C is distributed on two metal spheres. When the spheres are 10.00 cm apart, they each feel a repulsive force of 4.2*10^11 N. How much charge is on the sphere which has the lower amount of charge?

2). 2 equal charges, 10 micro Coulomb each, are separated by 5 cm. Find force between those.

3). Add 7 micro Coulombs and 4,204 nano Coulombs and get the result in nano Coulombs unit.

4). How many excess electrons can be counted in a rubber rod of - 5 *0.00001 nano Coulombs of charges?

5). A metal ball has - 4 Coulomb of charge. If it receives 0.50*10^20 number of electrons, what will be the resultant charge of the ball?

Answer 1

1) let the charges are q and Q.

given : q + Q = 3.3 C ----(i)

r = separation between the charges = 10 cm = 0.1 m

F = force between the charges =

According to Coluomb's Law :

-----(ii)

From (i) and (ii) :

the values of q = 3.1518 C and 0.1482 C

therefore, the smaller charge is 0.1482 C. [answer]

2) given :

2 identical charges each having charge q = 10 micro coulomb

sepration between them = r = 5 cm = 0.05 m

According to Coluomb's Law :

[answer]

3) given :

q = 7 micro coulomb = 7000 nano coulomb

Q = 4,204 nano coulomb

then, q + Q = 7000 + 4204 = 11204.0000 nano coulomb [answer]

4) given : q = - 5 *0.00001 nano coulomb =

Now, the charge on a body : q = ne [where n= no of electrons lost or gain, e = elctronic charge]

Number of excess electrons is 312500.[answer]

5) given :

initial charge = q = -4 C

n = number of electrons added = 0.50*10^20

charge added is [-ve sign is used, because electrons is added]

Therefore, net charge = q+Q = -4+(-8) = -12 C [answer]