MCQExams
0:0:1
CBSE
JEE
NTSE
NEET
Practice
Homework
×
CBSE Questions for Class 12 Medical Physics Electric Charges And Fields Quiz 2 - MCQExams.com
CBSE
Class 12 Medical Physics
Electric Charges And Fields
Quiz 2
If two bodies A and B (A bigger in size than B) are rubbed together, then :
Report Question
0%
A and B get equal and opposite charges
0%
A and B get equal and similar charges
0%
A gets more charge than B, but of opposite kind
0%
A gets less charge than B, but of same kind
Explanation
Answer is A.
Static electricity is created when two objects are rubbed together, causing an object to give up or gain electrons. The electric charges that are created do not depend on the size of the objects. Therefore,
when two bodies are rubbed together, both the bodies transfer electrons to and fro between the bodies and they obtain equal and opposite charges.
The body that gives away electrons, gains positive charge and the body that obtains electrons gains negative charge.
A negatively charged rod is brought close to two metal spheres which are in contact with each other and the spheres are separated in the presence of the rod. Then :
Report Question
0%
the sphere close to the rod acquires a negative charge and the other sphere acquires a positive charge
0%
the sphere close to the rod acquires a positive charge and the other sphere acquires a negative charge
0%
both the spheres will acquire positive charge
0%
both the spheres will acquire negative charge
Explanation
Since the rod which was brought closer was negatively charged the induced charge acquired by the spheres will be positive.
State the kind of charge on a negative ion :
Report Question
0%
positive
0%
negative
0%
zero
0%
cant say
Explanation
An ion is an atom or molecule in which the total number of electrons is not equal to the total number of protons, giving the atom or molecule a net positive or negative electrical charge.
It is an electrically charged atom or group of atoms formed by the loss or gain of one or more electrons. The valence of an ion is equal to the number of electrons lost or gained and is indicated by a plus sign for cations and a minus sign for anions.
An anion or a negative ion is an ion with more electrons than protons, giving it a net negative charge (since electrons are negatively charged and protons are positively charged).
'When two bodies are rubbed together, charges on them are ___________'.
Report Question
0%
unequal in magnitude but same in kind
0%
equal in magnitude and of same kind
0%
equal in magnitude but opposite in kind
0%
unequal in magnitude but opposite in kind
Explanation
On rubbing an ebonite rod with fur or cat's skin, the electrons from the fur gets transferred to the ebonite rod. The fur now has a deficiency of electrons and so is positively-charged. On the other hand, the ebonite rod has an excess of electrons and hence is negatively-charged.
In the above example, the fur undergoes positive electrification. It should be noted that it is the electrons and not the protons that get transferred during positive (and negative) electrification.
Also, the amount of charges are the same except that the type of charge differs.
Therefore, the ratio of the magnitude of the equal and opposite charges in fur and ebonite rod is 1:1 and the fur is negatively charged while the ebonite rod retains the positive charge.
Hence, the statement is true.
The property between two charged ebonite rods is :
Report Question
0%
attraction
0%
repulsion
0%
both
0%
none
Explanation
If two ebonite rods A and B are separately rubbed with fur and then they are brought near each other, they repel each other.
State True or False :
When electrons are removed, the body is said to be negatively charged.
Report Question
0%
True
0%
False
Explanation
Answer is B.
We can say that objects that are charged contain unequal numbers of protons and electrons. Charged objects have an imbalance of charge - either more negative electrons than positive protons or vice versa. And neutral objects have a balance of charge - equal numbers of protons and electrons.
Therefore, when electrons are removed, the object obtains positive charge and the statement is false.
A soap bubble is given a negative charge, then its radius :
Report Question
0%
Decrease
0%
Increase
0%
Remains unchanged
0%
Can't say
Explanation
$$\bullet$$ As soap bubble is conductor, so by symmetry, the charge will distribute uniformly over the surface of bubble.
$$\bullet$$ Due to mutual repulsion between like charges over the surface, they will push the parts of soap film away from each other.
$$\bullet$$ Hence the radius of the bubble will Increase.
Hence Correct answer is B.
$$\textbf{Note:}$$ There will be a finite increase in radius of the bubble up to the point, when mutual Electrostatic repulsion of negative charges is balanced by the force of Surface tension of bubble and pressure forces from outside and inside.
An inflated balloon was pressed against a wall after it has been rubbed with a piece of synthetic cloth. It was found that the balloon sticks to the wall. What force might be responsible for the attraction between the balloon and the wall?
Report Question
0%
Gravitational
0%
Magnetic
0%
Electrostatic
0%
adhesive
Explanation
Electrostatic force is the phenomenon that results from slow-moving or stationary electrical charges. Specifically, electrostatic force is the physical reaction that holds together the electromagnetic field created by subatomic particles, such as electrons and protons. In order for electrostatic forces to remain cohesive, these particles need to independently maintain both positive and negative charges and react to each other accordingly.
When a balloon is rubbed with a cloth, the electrons from the atoms of the cloth enter the atoms of the balloon and the number of electrons in the atoms of balloon becomes more than the number of protons. Because of that, there is a negative charge in the balloon, and in the cloth the number of electrons in its atoms become less than the number of protons, so it's positively charged.
Therefore, due to this electrostatic force, the balloon sticks to the wall.
An electroscope is used:
Report Question
0%
to detect presence of charge on a body.
0%
to determine the nature of charge on a body.
0%
to measure the exact amount of charge on a body.
0%
for both A and B.
Explanation
Electroscope is a device which is use to detect whether a body is carrying charge and also to detect the nature of charge on the body.
Electric switches and appliances should be tested only with
Report Question
0%
Right hand
0%
Left hand
0%
Both hands
0%
Electric tester
Explanation
We should not touch the electric appliance with bare hands. To check the supply in the circuit, the electric tester should be used.
A charged glass rod attract a charged plastic straw
Report Question
0%
True
0%
False
0%
Ambiguous
0%
Data insufficient
Explanation
Answer is A.
The statement is true because, when a charged glass rod is brought near a charged plastic straw they are attracted to each other. This is because, the glass rod accepts excess electrons and becomes negatively charge and the plastic straw give away electrons and become positively charged.
Unlike charges attract each other.
The adjoining figure shows a negatively charged electroscope. If a negatively charged rod is brought close to, but not touching, the knob, the two leaves will :
Report Question
0%
move closer together
0%
move farther apart
0%
not move at all
0%
None of these
Explanation
Answer is B.
In this case, the given electroscope is negatively charged. If a negatively charged rod is brought close to, but not touching, the knob, the two leaves will move far apart as the like charges repel each other.
Like charges attract each other:
Report Question
0%
True
0%
False
Explanation
Answer is B.
The statement is false because only unlike poles attract each other. Like poles repel each other.
Who named positive and negative charges?
Report Question
0%
Faraday
0%
Gauss
0%
Benjamin Franklin
0%
Curie
Explanation
Answer is C.
In the 18th century, Benjamin Franklin
in America tried experiments with charges. It was Franklin who named the two kinds of electricity 'positive' and 'negative'. He even collected electric charges from thunderstorm clouds through wet string from a kite.
The device, which can be used to detect whether an object is charged, is:
Report Question
0%
telescope
0%
microscope
0%
electroscope
0%
none of the above
Explanation
Electroscope is a device that is used for detection and identification of charge on objects.
What happens when the end of the paper clip of electroscope is touched by hands?
Report Question
0%
Electric current is produced
0%
Foil strips remain as it is
0%
Foil strips collapse
0%
None of the above
Explanation
When the paper clip of electroscope is touched by hands, the foil strips collapse because
the charges on foil strips gets discharged through our body.
Sometimes you get a mild spark when you touch the metal surface of a car. What might be the reason?
Report Question
0%
Due to magnetic attraction, a spark is created
0%
Due to electrostatic charge residing on the metal as well as on skin, mild spark is observed
0%
Car tries to become neutral by donating electrons
0%
Its the only path to ground
Explanation
Negative electric charge often resides on the surface of metal of car. When you touch the car, electrostatic discharge occurs via your body and you get a mild spark.
......... found that there are two kinds of charge
Report Question
0%
Newton
0%
Benjamin Franklin
0%
Coulomb
0%
William Gilbert
Explanation
Benjamin Franklin (1706-1790) found that there are two kinds of electrical charges.
1. positive charge
2. negative charge
Option B is correct.
When a charged body is brought near an electroscope:
Report Question
0%
the strips of foils opens up.
0%
the strips of foils close.
0%
the strips open and close simultaneously.
0%
the strips neither open nor close.
Explanation
When a charged body is brought near the top conducting disc of an electroscope, the disc gets induced with charges. These charges run down to the metal strips hanging from the paper clip. Now as both the strips get similar charge, those repel each other and thus open up.
What will be the nature of charge on the metal paper clip of electroscope when a negatively charged body is brought in contact with it?
Report Question
0%
Positive
0%
Negative
0%
Partially positive
0%
None of the above
Explanation
The nature of charge will be negative. When a negatively charged body come in context with uncharged metal paper clip then some amount of negative change will transfer from changed body to metal clip. This phenomenon of change transfer is called Conduction.
Which is not an electrostatic phenomenon
Report Question
0%
Comb rubbed with hair attracts paper bits
0%
A blanket in winters in dark when scrambled gives electrical sparks
0%
Two people shaking hands feel a small spark in winters
0%
Heat is generated in a resistor carrying current
Explanation
(d) is based on Joule's Law.
Rest are electrostatic phenomenon.
What will be the nature of charge on the metal paper clip of electroscope when a positively charged body is brought in contact with it?
Report Question
0%
Positive
0%
Negative
0%
Partially negative
0%
None of the above
Explanation
In a given activity, one positively charged body is coming in contact with uncharged metal paper clip. in this process, positive charge will transfer from charged body to metal paper clip by conduction.
Electric charges which are under the action of electric forces are known as :
Report Question
0%
Electrostatic
0%
Electric flux
0%
Electric field
0%
Electric field lines
Explanation
Electrostatic : when the charges are under action of electric forces.
Electric flux : It is the measure of filed lines through a given area.
Electric field : the electric force per unit charge.
Electric field lines : it measure the nature of charges, field lines is outward form positive charges and inner-ward for negative charges.
If a glass rod is rubbed on silk cloth and then brought near the bits of paper it...... then.
Report Question
0%
Attracts
0%
Repel
0%
Both
0%
None
Explanation
If a ordinary glass rod is rubbed on the silk cloth is brought near bits of paper, it is found that they have acquired the attractive property. The glass rod get charged on rubbing.
Electric field at a distance r from infinitely long conducting sheet is proportional to :
Report Question
0%
$$r^{-1}$$
0%
$$r^{-2}$$
0%
$$r^{3/2}$$
0%
independent of r
Explanation
Electric field at a distance from an infinite conducting sheet carrying uniform charge density is given by $$\dfrac { \sigma }{ 2{ \varepsilon }_{ 0 } } $$. Thus, it is independent of $$r$$.
The value of the constant $$k$$ in coulomb's law is :
Report Question
0%
$$9\times10^3$$
0%
$$9\times10^5$$
0%
$$9\times10^7$$
0%
$$9\times10^9$$
Explanation
The Coulomb's constant, $$k=\dfrac{1}{4\pi\epsilon_0}=\dfrac{1}{4\pi\times (8.85\times 10^{-12})}=9\times 10^9$$
What is known as electrostatic attraction?
Report Question
0%
When negatively charged atom is attracted towards positively charged atom
0%
When positively charged atom is attracted towards negatively charged atom
0%
When positively charged atom is attracted towards positively charged atom
0%
When negatively charged atom is attracted towards negatively charged atom
Explanation
When negatively charged atom is attracted towards positively charged atom and vice-versa, it is known as electrostatic attraction.
Options A, B are correct.
If a comb is rubbed on dry hairs, and then brought near paper pieces, it :
Report Question
0%
attracts paper
0%
repels paper
0%
remains indifferent to paper
0%
either attracts or repels paper
Explanation
If we bring small bits of paper near a rubber (or plastic) comb, it is found that the comb does not attract the bits of paper. But if the same comb is first rubbed on dry hairs and then it is brought near the paper pieces, it attracts them.
.......... Property develops in comb due to friction.
Report Question
0%
Attractive
0%
Repulsive
0%
Both
0%
None
Explanation
An attractive property is develop in the comb due to friction. The comb on rubbing over dry hairs is aid to be charged.
The law that describes the force as directly proportional to magnitude of charges and inversely proportional to the distance between the charges is known as :
Report Question
0%
Newton's law
0%
Coulomb's law
0%
Gauss's law
0%
Ohm's law
Explanation
Newton's law : force $$F=ma$$ where m=mass and a=acceleration
Coulomb's law : force $$F=\dfrac{kq_1q_2}{r^2}$$ where $$q_1, q_2 $$ are charges and $$r=$$ separation of charges and $$k=$$ proportionality constant.
Gauss's law : the electric flux $$\phi=\dfrac{q}{\epsilon_0}$$
Ohm's law : Potential across a wire of resistance R is $$V=IR$$ where I is the current.
On which factors from below does Coulomb's law(i.e. law of electrostatic attraction and repulsion) depends?
Report Question
0%
Magnitude of charges
0%
Distance between charges
0%
Both magnitude and distance between charges
0%
None of the above
Explanation
Coulomb's Law : $$\dfrac{kq_1q_2}{r^2}$$
It depends on both magnitude of charges and distance between them.
Which of the following materials has a negative temperature coefficient of resistance?
Report Question
0%
Copper
0%
Aluminium
0%
Carbon
0%
brass
Explanation
Carbon
has a negative temperature coefficient of resistance.
Option C is correct.
A closed switch has a resistance of :
Report Question
0%
zero ohm
0%
about $$50$$ ohms
0%
about $$500$$ ohms
0%
infinity
Explanation
A closed switch has a Zero resistance.
Option A is correct.
When we wear nylon dresses during winter then there is ______ current which gets produced due to contact with out body. Fill in the Blank.
Report Question
0%
Magnetic
0%
Electrostatic
0%
Potential
0%
kinetic
Explanation
When we wear nylon dresses during winter then there is electrostatic current which gets produced due to contact with out body.
Option B is correct.
The filament of an electric bulb is made of :
Report Question
0%
Carbon
0%
Aluminium
0%
Tungsten
0%
Nickel
Explanation
Hint:-Melting point of filament should be high
Explanation
:-
$$\bullet$$
The electric bulbs convert electrical energy to heat and light energy and thus the filaments of the bulbs are expected to withstand high temperatures
$$\bullet$$
While at the same time ensure that their structure does not get affected via heating effects from the current passing through
.
$$\bullet$$As a metal, Tungsten is a good electrical conductor. It is also a good thermal conductor. In pure form, tungsten has the highest known melting point among all metals and lowest vapour pressure
and greatest tensile strength out of all the metals.
$$\bullet$$This means that tungsten is able to maintain its form irrespective of the large heating effects from electrical current.
Because of this, It can reach a high temperature before melting.
$$\textbf{Hence option C correct}$$
In an external electric field, the field line of force represent:
Report Question
0%
the direction of the force experienced by a positively charged particle placed in the field
0%
the direction of the force experienced by a negatively charged particle placed in the field
0%
the direction that a negatively charged particle in the field would move
0%
how far the force field extends from the particle
0%
the strength of the force field
Explanation
The force experience by a particle $$q$$ in a force field $$\vec{E}$$ is given by $$\vec{F}=q\vec{E}$$.
Thus of a positively charged particle, $$q$$ is positive, and hence the direction of force on the particle and the field is the same.
Thus it can be said that the field line of force represent
the direction of the force experienced by a positively charged particle placed in the field.
Which is the best conductor of electricity?
Report Question
0%
Iron
0%
Silver
0%
Copper
0%
Carbon
Explanation
$$\textbf{Explanation}$$
$$\bullet$$Silver is the best conductor of electricity because it contains maximum number of free electrons.
$$\bullet$$Also the resistance of silver is very low.
$$\textbf{Hence option B correct}$$
When we rub our comb with hair and then take near to the paper pieces, all pieces get stuck to the comb. This happens due tyo which phenomena?
Report Question
0%
Electrostatic Induction
0%
Magnetic effect
0%
Potential effect
0%
Kinetic effect
Explanation
When negative charges is created in the comb by rubbing it with hair and pieces of paper are exposed to the electric field created by the charge, the part of paper closer to the comb will be positively charged due to electromagnetic induction, and the farther would be negatively charged, causing the paper to be attracted to the comb.
The force between two bodies having charges $$5C$$ and $$10C$$ separated by distance of $$0.5 m$$ in air is :
Report Question
0%
$$18\times 10^{11}\ N$$
0%
$$9\times 10^{11}\ N$$
0%
$$9\times 10^{9}\ N$$
0%
$$18\times 10^{9}\ N$$
Explanation
By Coulomb's law, the force between two charges is $$F=k \dfrac{q_1q_2}{r^2}=(9\times 10^9)\times \dfrac{5\times 10}{(0.5)^2}=18\times 10^{11} N$$
A negative ion is an object that has
Report Question
0%
More electrons than neutrons
0%
More electrons than protons
0%
More protons that neutrons
0%
More protons than electrons
0%
More neutrons than electrons or protons
Explanation
An atom is electrically neutral because it has equal number of electrons (-ive) and protons (+ive) , when atom receives electrons from somewhere , amount of negative charge becomes greater than positive charge ,so net charge =-ive , and atom turns into negative ion .Now negative ion has more electrons than protons.
Electric lines of force about a negative point charge are:
Report Question
0%
Circular anti-clockwise
0%
Circular clockwise
0%
Radially inwards
0%
Radially outwards
Explanation
Hint:- Use the properties of electric field lines.
Explanation:-
$$\bullet$$ Electric field lines are always originated from positive charge and end at negative charge.
$$\bullet$$ Electric field lines are perpendicular to the surface of point charge.
So for a negative point charge electric field lines are radially inwards.
Hence option C is correct
Identify which of the following diagrams best represents the electric field lines around a positive charge?
Report Question
0%
0%
0%
0%
0%
Explanation
Electric field lines originate at the positive charge and diverge (spread) in all directions into the space and end at the negative charge.
Thus option B is correct.
A charged particle is accelerated by a potential of 200V. If its velocity is $$8.4\times 10^8m/s$$, then value of e/m for that particle in $$C/kg$$ is:
Report Question
0%
$$17.6\times 10^{16}$$
0%
$$14.5\times 10^{12}$$
0%
$$1.76\times 10^{15}$$
0%
$$1.45\times 10^{15}$$
Explanation
Work done = Change in KE
$$eV=\dfrac { 1 }{ 2 } m{ v }^{ 2 }\\ \Rightarrow \dfrac { e }{ m } =\dfrac { { v }^{ 2 } }{ 2V } =\dfrac { { \left( 8.4\times { 10 }^{ 8 } \right) }^{ 2 } }{ 400 } =1.76\times { 10 }^{ 15 }$$
The existence of a negative charge on a body implies that it has:
Report Question
0%
Lost some of its electrons
0%
Lost some of its protons
0%
Acquired some electrons from outside
0%
Acquired some protons from outside
Explanation
An atom or a body as a whole itself is neutral with equal no. of electrons and protons.
But a body acquires some electrons from outside then it gets negatively charged.
Electroscope is used
Report Question
0%
to detect and test small electric charges
0%
to calculate the amount of electric charge flowing through the conductor in the given interval of time
0%
to find out the presence of antimatter
0%
to test the presence of magnetic field
Explanation
Electroscope is an old electrical instrument , used to detect the presence and magnitude of electric charges on a body .
In the diagram, three point charges (labeled 1, 2 and 3) are shown, along with the electric field around them. Which charge(s) is/are positive?
Report Question
0%
2 only
0%
1 and 2
0%
1 and 3
0%
1, 2 and 3
Explanation
The electric field always originate at the positive charge and terminate at the negative charge.
From figure, the electric field lines originate at the points 1 and 3 but ends at point 2.
Thus points 1 and 3 represent positive charge and 2 represents the negative charge.
A charge can exist without mass.
Report Question
0%
True
0%
False
Explanation
The statement that "a charge can exist without mass" is false. This is because none of the fundamental particles that form the Standard Model have charge without mass. The St
andard Model describes all energy and matter that makes up the universe, except gravitation. And gravitation does not have charge, it has mass.
Coulomb's law is applicable only to stationary electric charges.
Report Question
0%
True
0%
False
Explanation
The statement that the "Coulomb's law is applicable to only stationary electric charges" is true. This is because in case of moving charges, there is a current, which generates magnetic field that in turn exerts force on moving charges, therefore we no longer consider Coulomb's Force alone.
Electric charge is measured in
Report Question
0%
coulombs
0%
amperes
0%
volts
0%
watts
Explanation
The standard unit of charge is coulomb (C). Here ampere is the unit of current, volts is the unit of electric potential difference and watts is the unit of power.
One point electric charge $$Q$$ is placed at the point $$P$$. A closed surface is placed near the point $$P$$. The electrical flux passing through a closed surface will be _________.
Report Question
0%
$$Q\epsilon_{0}$$
0%
$$\epsilon_{0}/ Q$$
0%
$$Q/ \epsilon_{0}$$
0%
Zero
Explanation
Since, the charged is outside the closed surface.
$$\therefore$$ The electric flux through the closed surface will be zero.
As, $$\phi=\cfrac{\phi_{net}}{\epsilon_o}$$
$$\phi_{net}=0$$
$$\therefore \phi=0$$
0:0:1
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
0
Answered
0
Not Answered
0
Not Visited
Correct : 0
Incorrect : 0
Report Question
×
What's an issue?
Question is wrong
Answer is wrong
Other Reason
Want to elaborate a bit more? (optional)
Practice Class 12 Medical Physics Quiz Questions and Answers
<
>
Support mcqexams.com by disabling your adblocker.
×
Please disable the adBlock and continue.
Thank you.
Reload page
