Two similarly and equally charged identical metal spheres A and B repel each other with a force of 2 . 0 × 10 - 5 N . A third identical, uncharged sphere C is touched with A and then placed at the mid-point between A and B . What is net electric force on C ?

In first condition, q 1 = q 2 = q Force of repulsion = F = 2 . 0 × 10 - 5 N F = 1 4 π ϵ 0 · q 2 r 2 = 9 × 10 9 q 2 r 2 q 2 r 2 = 2 × 10 - 5 9 × 10 9 = 2 9 × 10 - 14 When uncharged sphere C touched with A , then charge on A and C = q + 0 2 = q 2 Now C , is placed at middle of A and B F net at sphere C = F eA - F eB = 1 4 π ε 0 . q 2 · q 2 ( r / 2 ) 2 - 1 4 π ϵ 0 · q · q / 2 ( r / 2 ) 2 = 1 4 π ϵ 0 · q 2 × 4 4 r 2 - 1 4 π ϵ 0 · q 2 × 4 2 r 2 = 1 4 π ε 0 · q 2 r 2 [ 1 - 2 ] = - 1 4 π ε 0 · q 2 r 2 = - 2 . 0 × 10 - 5 N Magnitude of net force = 2 . 0 × 10 - 5 N - ve sign indicates that direction will be opposite to B mean towards A

MEDIUM

12th ICSE

IMPORTANT

Earn 100

How far apart the two electrons be, if the force between them equals the weight of an electron? What in case of protons?

Important Questions on Electric Charges and Fields

HARD

12th ICSE

IMPORTANT

NOOTAN ISC PHYSICS Class 12 Part-1>Chapter 1 - Electric Charges and Fields>QUESTIONS>Q 6

Two positive charges distant

0.1 m

apart, repel each other with a force of

18 N

. If the sum of the charges be

9

micro-coulomb

(μC)

, then calculate their separate values.

MEDIUM

12th ICSE

IMPORTANT

NOOTAN ISC PHYSICS Class 12 Part-1>Chapter 1 - Electric Charges and Fields>QUESTIONS>Q 7

The distance between two negatively-charged dust particles is $1 mm$ and they repel each other with a force of $4.0 \times 10^{- 5} N$ . If the charge on one particle is $4$ times that of the other, then find out the number of electrons charging them separately. The charge on electron is $(5 / 3) \times 10^{- 19} C$ .

MEDIUM

12th ICSE

IMPORTANT

NOOTAN ISC PHYSICS Class 12 Part-1>Chapter 1 - Electric Charges and Fields>QUESTIONS>Q 8

Two point-charges of

+ 2 μC

and

+ 6 μC

, repel each other with a force of

12 N

. If each is given an additional charge of

- 4 μC

, then what will be the new force?

MEDIUM

12th ICSE

IMPORTANT

NOOTAN ISC PHYSICS Class 12 Part-1>Chapter 1 - Electric Charges and Fields>QUESTIONS>Q 9

Two identical metallic balls

A

and

B

have charges

+ 40

and

- 10 μC

respectively. The distance between them is

2.0 m

. What is the magnitude and type of force acting between them? They are touched to each other and again separated by a distance of

2.0 m

from each other. Calculate the new force between them. What will be the force if one ball is connected to earth?

HARD

12th ICSE

IMPORTANT

NOOTAN ISC PHYSICS Class 12 Part-1>Chapter 1 - Electric Charges and Fields>QUESTIONS>Q 10

Two similarly and equally charged identical metal spheres

A

and

B

repel each other with a force of

2.0 \times 10^{- 5} N

. A third identical, uncharged sphere

C

is touched with

A

and then placed at the mid-point between

A

and

B

. What is net electric force on

C

HARD

12th ICSE

IMPORTANT

NOOTAN ISC PHYSICS Class 12 Part-1>Chapter 1 - Electric Charges and Fields>QUESTIONS>Q 11

Two conducting spheres

A

and

B

of the same size are situated at some distance apart. Each has a charge of

+ q

Coulomb and they repel each other with a force of

10^{- 5} N

. A third conducting uncharged sphere

C

of same size is first touched with $A$ and then with $B$ and then placed exactly between

A

and

B

. Calculate the resultant force on

C

MEDIUM

12th ICSE

IMPORTANT

NOOTAN ISC PHYSICS Class 12 Part-1>Chapter 1 - Electric Charges and Fields>QUESTIONS>Q 12

In the adjoining figures are shown three particles $A$ , $B$ and $C$ which are equally charged. The force acting on $B$ due to $A$ is $2.0 \times 10^{- 6} N$ . Find out in each Fig. $(i)$ force exerted on $B$ by $C$ ,

Question Image

HARD

12th ICSE

IMPORTANT

NOOTAN ISC PHYSICS Class 12 Part-1>Chapter 1 - Electric Charges and Fields>QUESTIONS>Q 12

In the adjoining figures are shown three particles

A

B

and

C

which are equally charged. The force acting on

B

due to

A

2.0 \times 10^{- 6} N

. Find out in each Fig.

(ii)

net force on

B

How far apart the two electrons be, if the force between them equals the weight of an electron? What in case of protons?

Important Questions on Electric Charges and Fields

Learn and Prepare for any exam you want !