Two insulated charge copper spheres A and B have their centres separated by a distance of 50 cm . The charge on each of them is 6 . 5 × 10 - 7 C . What is the force of repulsion if each sphere is charged double the above amount, and the distance between them is halved? (Take 1 4 π ∈ 0 = 9 × 10 9 )

Given, The initial charge, q = 6 . 5 × 10 - 7 C The initial distance, d = 50 cm = 0 . 5 m As the charge on each sphere is doubled, the charges on them respectively are, q A = q B = 2 × q = 2 × 6 .5 × 10 - 7 C = 1 .3 × 10 - 6 C Distance between the spheres is halved, so the new distance, r = d 2 = 0 .5 2 = 0 .25 m We know that the force is given by, F = q A q B 4 π ∈ 0 r 2 = 9 × 10 9 × 1.3 × 10 - 6 × 1.3 × 10 - 6 ( 0.25 ) 2 = 0.243 N

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An electrostatic field line is a continuous curve. That is, a field line cannot have sudden breaks. Why not?

Important Questions on Electric Charges and Fields

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PHYSICS PART-1 TEXTBOOK FOR CLASS XII>Chapter 1 - Electric Charges and Fields>EXERCISES>Q 1.7

Explain why two field lines never cross each other at any point?

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PHYSICS PART-1 TEXTBOOK FOR CLASS XII>Chapter 1 - Electric Charges and Fields>EXERCISES>Q 1.8

Two point charges

q_{A} = 3 µ C

and

q_{B} = - 3 μC

are located

20 cm

apart in vacuum. What is the electric field at the midpoint

O

of the line

AB

joining the two charges? If a negative test charge of magnitude

1.5 \times 10^{- 9} C

is placed at this point, what is the force experienced by the test charge? Take,

\frac{1}{4 π \in_{0}} = 9 \times 10^{9} {Nm}^{2} C^{- 2}

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PHYSICS PART-1 TEXTBOOK FOR CLASS XII>Chapter 1 - Electric Charges and Fields>EXERCISES>Q 1.9

A system has two charges

q_{A} = 2.5 \times 10^{- 7} C

and

q_{B} = - 2.5 \times 10^{- 7} C

located at points

A

(0, 0, - 15 cm)

and

B

(0, 0, 15 cm)

, respectively. What is the total charge and electric dipole moment of the system?

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PHYSICS PART-1 TEXTBOOK FOR CLASS XII>Chapter 1 - Electric Charges and Fields>EXERCISES>Q 1.1

An electric dipole with dipole moment

4 \times 10^{- 9} C m

is aligned at

30^{°}

with the direction of a uniform electric field of magnitude

5 \times 10^{4} N C^{- 1}

. Calculate the magnitude of the torque acting on the dipole.

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PHYSICS PART-1 TEXTBOOK FOR CLASS XII>Chapter 1 - Electric Charges and Fields>EXERCISES>Q 1.11

A polythene piece rubbed with wool is found to have a negative charge of

3 \times 10^{- 7} C

. Estimate the number of electrons transferred. Is there a transfer of mass from wool to polythene? (The charge of the electron,

e = - 1 .6 \times 10^{- 19} C

)

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PHYSICS PART-1 TEXTBOOK FOR CLASS XII>Chapter 1 - Electric Charges and Fields>EXERCISES>Q 1.12

Two insulated charged copper spheres

A

and

B

have their centers separated by a distance of

50 cm

. What is the mutual force of electrostatic repulsion if the charge on each is

6.5 \times 10^{- 7} C

?
The radii of

A

and

B

are negligible compared to the distance of separation. (Take,

\frac{1}{4 {πε}_{0}} = 9 \times 10^{9}

)

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PHYSICS PART-1 TEXTBOOK FOR CLASS XII>Chapter 1 - Electric Charges and Fields>EXERCISES>Q 1.12

Two insulated charge copper spheres $A$ and $B$ have their centres separated by a distance of $50 cm$ . The charge on each of them is $6.5 \times 10^{- 7} C$ . What is the force of repulsion if each sphere is charged double the above amount, and the distance between them is halved? (Take $\frac{1}{4 π \in_{0}} = 9 \times 10^{9}$ )

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PHYSICS PART-1 TEXTBOOK FOR CLASS XII>Chapter 1 - Electric Charges and Fields>EXERCISES>Q 1.13

Suppose there are two copper spheres

A

and

B

having identical sizes. The distance between the centers of sphere is

50 cm

and the charge on each sphere is

6.5 \times 10^{- 7} C

. A third sphere of the same size but uncharged is brought in contact with the first, then brought in contact with the second, and finally removed from both. What is the new force of repulsion between

A

and

B

An electrostatic field line is a continuous curve. That is, a field line cannot have sudden breaks. Why not?

Important Questions on Electric Charges and Fields

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