Charging by Conduction

Q. When a body is earth connected, electrons from the earth flow into the body. This means the body is…..

1. Charged positively
2. Charged negatively
3. An insulator
4. Unchanged

Q. Suppose the spheres A and B in Exercise 1.12 have identical sizes.A third sphere of the same size but uncharged is brought in contactwith the first, then brought in contact with the second, and finallyremoved from both. What is the new force of repulsion between Aand B?

Q. In general, metallic ropes are suspended on the carriers which take inflammable material. The reason is

1. There speed is controlled
2. To keep the centre of gravity of the carrier nearer to the earth
3. To keep the body of the carrier in contact with the earth
4. Nothing should be placed under the carrier

Q.

A point charge $+q$, is placed at a distance d from an isolated conducting plane. The field at a point $P$ on the other side of the plane is

1. directed perpendicular to the plane but towards the plane.

2. directed radially towards the point charge

3. directed perpendicular to the plane and away from the plane.

4. directed radially away from the point charge.

Q. Five charges $q_1,q_2,q_3,q_4\text{and}{q}_5$ are fixed at their positions as shown in Figure. $S$ is a Gaussian surface. The Gauss’s law given by which of the following statements is correct?

$\oint \overrightarrow{E}.\overrightarrow{ds}=\frac{q}{{\epsilon }_0}$

1. $E$ on the LHS of the above equation will have a contribution from $q_1,q_5\text{and}{q}_3$ while $q$ on the RHS will have a contribution from $q_2\text{and}{q}_4$ only.

2. $E$ on the LHS of the above equation will have a contribution from all charges while $q$ on the RHS will have a contribution from $q_2\text{and}{q}_4$only.
   
3. $E$ on the LHS of the above equation will have a contribution from all charges while $q$ on the RHS will have a contribution from $q_1,q_3\text{q\_5}$ only
4. Both $E$ on the LHS and $q$ on the RHS will have contributions from $q_2\text{and}{q}_4$ only.
   

Q. Can there be a potential difference between two adjacent conductors carrying the same charge?

Q.

Why did the leaves of the electroscope collapse on touching?

1. Electroscope doesn’t work when touched with hand.

2. The charge on the leaves was conducted through the hand into the earth.

3. Charges disappear sometimes

4. Charges dissipated into the air inside the electroscope

Q. Van de Graaff generators works on the principles of

1. corona discharge or sharp point action
2. net charge always resides on the outer surface of the conductor
3. charged particle creates a magnetic field
4. All of the above

Q. What is earthing?

Q. Two metallic spheres of radii $1cm$ and $3cm$ are given charges of $-1\times {10}^{-2}C$ and $5\times {10}^{-2}C$ respectively. If these are connected by a conducting wire, the final charge on the bigger sphere is

1. $2\times {10}^{-2}C$
2. $3\times {10}^{-2}C$
3. $4\times {10}^{-2}C$
4. $1\times {10}^{-2}C$

Q. A: It is easier to charge a balloon on a dry daythan on a humid day.R: Dryness allows some charge to leak from theballoon.

Q.

What happens to the flow of charges when the potential difference between two points becomes zero?

Q.

What do earthing and grounding mean?

Q. a polythene piece rubbed with wool is found to have a negative charge of 3.2 * 10^-7. Find the mass gained by polythene

Q.

What happens if earthing is not proper in a telegraph?

Q. Equal charges $Q$ are placed at the four corners $A,B,C,D$ of a square of length $a$. The magnitude of the force on the charge at $B$ will be

1. $\frac{3Q^2}{4\pi {ϵ}_0{a}^2}$
   
2. $(2+\frac{1}{\sqrt{2}})\frac{Q^2}{4\pi {ϵ}_0{a}^2}$
   
3. $\left(\frac{1+2\sqrt{2}}{2}\right)\frac{Q^2}{4\pi {ϵ}_0{a}^2}$
   
   
4. $\frac{4Q^2}{4\pi {ϵ}_0{a}^2}$
   
   

Q. the principle of van de graaff generator is 1)electrostatic shielding 2)corona discharge 3)conduction 4) both 1 and 3

Q.

For current to flow, one needs a,

1. Closed circuit

2. Source of potential difference

3. Both (a) and (b)

4. Infrared radiation

Q.

When a body is earth connected, electrons from the earth flow into the body. This means that body is...

BOOK ANSWER - Uncharged

My Answer

I know two things that electrons can be moved to:

Positively charged body

Negatively charged body (by forcing the electrons)

Neutral body

But book answer tell that body will only be Uncharged and according to me body can be charged or Uncharged.

Where I am going wrong?

Q. what is van de graaff generator?

Q. Two-point charges $q_1\left(\sqrt{10}\mu C\right)$ and $q_2(-25\mu C)$ are placed on the $x-$axis at $x=1m$ and $x=4m$, respectively. The electric field (in $V/m$) at a point $y=3m$ on $y-$axis is $[\text{take}\frac{1}{4\pi {\epsilon }_0}=9\times {10}^{9}N{m}^2{C}^2]$

1. $(-81\hat{i}+81\hat{j})\times {10}^2$
2. $(-63\hat{i}+27\hat{j})\times {10}^2$
3. $(63\hat{i}-27\hat{j})\times {10}^2$
4. $(81\hat{i}-81\hat{j})\times {10}^2$

Q. In general, metallic ropes are suspended on the carriers which take inflammable material. The reason is

1. There speed is controlled
2. To keep the centre of gravity of the carrier nearer to the earth
3. To keep the body of the carrier in contact with the earth
4. Nothing should be placed under the carrier

Q.

Why does lighting strikes only at sharp edges like leaves of trees??

Q. The electric field on two sides of a large charged sheet is shown in the figure. The charge density on the sheet in $\text{SI}$ units is given by $({\epsilon }_0$ is the permittivity of free space in $\text{SI}$ units $)$

1. $2{\epsilon }_0$
2. Zero.
3. $4{\epsilon }_0$
4. $10{\epsilon }_0$

Q.

When a body is earth connected electrons from earth flow into the body.the means the body is

Q. A charged particle (electron or proton) is introduced at the origin $(x=0,y=0,z=0)$ with a given initial velocity $\overrightarrow{v}$. A uniform electric field $\overrightarrow{E}$ and a uniform magnetic field $\overrightarrow{B}$ exist everywhere. The velocity$\overrightarrow{v}$, electric field $\overrightarrow{E}$ and magnetic field $\overrightarrow{B}$ are given in columns 1, 2 and 3, respectively. The quantities $E_0,B_0$ are positive in magnitude.

In which case will the particle move in a straight line with constant velocity?

1. (III) (ii) (R)
2. (IV) (i) (S)
3. (II) (iii) (S)
4. (III) (iii) (P)

Q.

Earthing or grounding means

1. sharing the charges with the earth

2. placing the apparatus with an insulating stand, on the ground

3. using green color to paint the body

4. connecting to a green colored wire

Q.

Why are the safety devices used in electrical connections?

Q. 2.What will happen to the leaves of an electroscope if a positively charged body is brought near to an uncharged electroscope?

Q.

When a body is earthed, electrons flow from the earth into the body. This means the body is

1. charged positively

2. an insulator

3. charged negatively

4. uncharged