Electric Charges and Fields Test 2

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Electric Charges and Fields Test 2

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Weekly Quiz Competition

Question 1
1 / -0

Which of the following methods can be used to charge a metal sphere positively without touching it . Select the best

A
Connect the positive terminal of a battery and float the other end of the battery

B
Rub it with a piece of fur

C
Bring a negatively charged rod near the sphere and touch it to ground for a short while

D
Rub it with a piece of silk

Solution

This can be possible by induction, if a negative charge rod is placed near the sphere (at a distance not in touch) than it attracts positive charge inside the sphere towards its side and the negative charges collected on other side and when the surface of sphere connected to earth than the negative charge goes to earth and the sphere remain positively charged.
Question 2
1 / -0

When a negatively charged conductor is connected to earth,

A
No charge flow occurs.

B
Protons flow from the conductor to the earth.

C
Electrons flow from the earth to the conductor.

D
Electrons flow from the conductor to the earth.

Solution

After earthing a positively charged conductor electrons flow from earth to conductor and if a negatively charged conductor is earthed then electrons flows from conductor to earth.
Question 3
1 / -0

A point charge of 2.0 μC is at the centre of a cubic Gaussian surface 9.0 cm on edge. What is the net electric flux through the surface?

A
1.7×10⁵Nm²/C

B
2.1×10⁵Nm²/C

C
2.2×10⁵Nm²/C

D
1.9×10⁵Nm²/C

Solution
Question 4
1 / -0

Two identical conductors of copper and aluminium are placed in an identical electric field. The magnitude of induced charge in the aluminium will be:

A
Zero

B
Equal to that of copper

C
Greater than in copper

D
less than in copper

Solution

As aluminium and copper are metals, their mobile electrons move under the influence of the external field until they reach the surface of the metal and collect there. External electric fields induce surface changes on metal objects that exactly cancel the field within. Since the field applied is same in both case, the induced charge will be the same. Hence, the magnitude of induced charge in the aluminium will be the same as that of copper.
Question 5
1 / -0

A point charge causes an electric flux of −1.0×10³Nm²/C to pass through a spherical Gaussian surface of 10.0 cm radius centred on the charge.
(a) If the radius of the Gaussian surface were doubled, how much flux would pass through the surface?
(b) What is the value of the point charge?

A
10³Nm²/C,−7.8nC

B
10³Nm²/C,−8.8nC

C
−10³Nm²/C,−8.8nC

D
−10³Nm²/C,−6.8nC

Solution

Electric flux is given by since amount of charge not depends on size and shape so by making radius < double the amount of charge remain same so electric flux remain same.
Question 6
1 / -0

Electric charge:

A
Is a property of protons only.

B
Is a property of particles such as atoms, ions, electrons, etc.

C
Is a property of neutrons only.

D
Is a property of electrons only.

Solution

Electric charge, the basic property of matter carried by some elementary particles, such as atoms; ions; electrons; etc, that govern how the particles are affected by an electric or magnetic field.
Electric charge, which can be positive or negative, occurs in discrete natural units and is neither created nor destroyed.
Question 7
1 / -0

An electric dipole is

A
A pair of electric charges of equal magnitude q separated by a distance d

B
A pair of electric charges of equal magnitude q but positive sign, separated by a distance d

C
A pair of electric charges of equal magnitude q but opposite sign, separated by a distance

D
A pair of electric charges of equal magnitude q but negative sign, separated by a distance d

Solution

An electric dipole is a separation of positive and negative charges. The simplest example of this is a pair of electric charges of equal magnitude but opposite sign, separated by some (usually small) distance. A permanent electric dipole is called an electret.
Question 8
1 / -0

A hollow spherical conductor of radius 2m carries a charge of 500 μ C. Then electric field strength at its surface is

A
4.5×10⁶N/C

B
Zero

C
2.25×10⁶N/C

D
1.125×10⁶N/C .

Solution
Question 9
1 / -0

For forming an electric dipole between two point charges separated by a small distance, the two point charges are of

A
Unequal magnitude and opposite sign

B
Unequal magnitude but same sign

C
Equal magnitude and same sign

D
Equal magnitude but opposite sign

Solution

An electric dipole is tagged as a pair of objects which possess equal & opposite charges, parted by a significantly small distance.
Question 10
1 / -0

The amount of work done in moving a charge from one point to another along an equipotential line or surface charge is

A
Zero

B
Infinity

C
One

D
Two

Solution

Since Potential difference between two points in equipotential surfaces is zero , the work done between two points in equipotential surface is also zero .
Question 11
1 / -0

An electric field can deflect

A
X rays

B
α – rays

C
γ - rays

D
Neutrons

Solution

Only alpha rays are moving with small velocity and having charge so they will be affected by electric field.
Question 12
1 / -0

Under the influence of the coulomb field of charge +Q, a charge −q is moving around it in an elliptical orbit. Find out the correct statement(s).

A
The linear momentum of the charge −q is constant

B
The angular velocity of the charge −q is constant

C
The angular momentum of the charge −q is constant.

D
The linear speed of the charge −q is constant

Solution

Since the charge –q is moving in elliptical orbit so to make its motion stable the total angular momentum of the charge is constant since it experience a centripetal force from the charge +Q so it follow the motion as the motion of earth around sun.
Question 13
1 / -0

Conservation of charges in tribo electric charging

A
Implies both are negatively charged.

B
Implies half are positively charged and the other half are neutral.

C
Implies one is positively charged and the other is negatively charged.

D
Implies both are positively charged.

Solution

The triboelectric effect (also known as triboelectric charging) is a type of contact electrification in which certain materials become electrically charged after they come into frictional contact with a different material.
Example: Rubbing glass with fur, or a plastic comb through the hair.
When we charge something with static electricity, no electrons are made or destroyed. Electrons are just moved from one place to another. The net electric charge stays the same. This is called the principle of conservation of charge.
i.e. If a glass rod is rubbed with silk, some electrons moves from glass rod to silk no new charge is generated or destroyed.
Question 14
1 / -0

Consider a neutral conducting sphere. A positive point charge is placed outside the sphere. The net charge on the sphere is then,

A
Negative and distributed non–uniformly over the entire surface of the sphere

B
Negative and distributed uniformly over the surface of the sphere.

C
Negative and appears only at the point on the sphere closest to the point charge

D
Zero.

Solution

If a charge q is placed outside than the electric field lines incident on the conducting sphere , if some charge is developed due to thee lines than opposite surface becomes oppositely charge and the total charge becomes zero.
Question 15
1 / -0

Two positive charges

A
Repel each other

B
Attract each other at times and repel at other times

C
Attract each other

D
Always attract each other

Solution

Acc to coulomb's law unlike charges always attract each other while like charges always repel each other.
Question 16
1 / -0

Ionization of a neutral atom is the

A
Only gain of one or more electrons

B
Only gain of one or more protons

C
Gain or loss of one or more electrons

D
Only gain of one or more neutrons

Solution

It is not possible to remove or add protons/neutrons to an atom, but electrons can be added or removed by an atom easily.
By adding electrons it becomes negatively charged.
By removing electrons it becomes positively charged.
Question 17
1 / -0

A charge q is placed at the center of the line joining two equal charges Q. The system of the three charges will be in equilibrium if q is equal to

A
Q/2

B
-Q/4

C
Q/5

D
Q/3

Solution

Suppose in the following figure, equilibrium of charge B is considered. Hence for its equilibrium,
Question 18
1 / -0

The electrostatic force is:

A
Force exerted by an electron on a neutron.

B
Force exerted by one charge on another when the two are at rest in a given frame of reference.

C
Force exerted by one charge on another when the two are moving in a given frame of reference.

D
Force exerted by one charge on another when the two are accelerating in a given frame of reference.

Solution

The electrostatic force is an attractive and repulsive force between particles are caused due to their electric charges. The electric force between stationary charged bodies is conventionally known as the electrostatic force.
Question 19
1 / -0

Two charges A = -2.50 μC and B = 6.0 μC are at a distance of 1 meter from each other. Distance from A at which the electric field is zero in meters is

A
2.03

B
1.85

C
2.22

D
1.92

Solution

where,
x = distance of the null point from the small charge
d = distance between two charges
q₂= bigger charge
q₁= small charge
+1 for like charges and -1 for unlike charges
Question 20
1 / -0

Conductors are materials

A
That allow movement of electrons

B
That allow movement of protons

C
That allow only random movement of electrons

D
That allow movement of neutrons

Solution

Conductors are materials that permit electrons to flow freely from particle to particle. An object made of a conducting material will permit a charge to be transferred across the entire surface of the object.