MCQ 11 Mark
For two statements are given $-$ one labelled Assertion $(A)$ and the other labelled Reason $(R)$. Select the correct answer to these questions from the codes $\ce{(a), (b), (c)}$ and $(d)$ as given below:
Assertion : In electric circuits, wires carrying currents in opposite directions are often twisted together.
Reason : If the wire are not twisted together, the combination of the wires forms a current loop. The magnetic field generated by the loop might affect adjacent circuits or components.
- ✓
Both $A$ and $R$ are true, and $R$ is correct explanation of the assertion.
- B
Both $A$ and $R$ are true, but $R$ is not the correct explanation of the assertion.
- C
$A$ is true, but $R$ is false.
- D
$A$ is false, but $R$ is true.
AnswerCorrect option: A. Both $A$ and $R$ are true, and $R$ is correct explanation of the assertion.
If the wires are twisted together, they can be modelled as a single wire carrying current in the opposite directions. ln this model, no magnetic field is induced in the wires which does not affect adjacent circuits.
View full question & answer→MCQ 21 Mark
For two statements are given $-$ one labelled Assertion $(A)$ and the other labelled Reason $(R)$. Select the correct answer to these questions from the codes $\ce{(a), (b), (c)}$ and $(d)$ as given below :
Assertion : When two long parallel wires, hanging freely are connected in parallel to a battery, they come closer to each other.
Reason : Wires carrying current in opposite directions repel each other.
- A
Both $A$ and $R$ are true, and $R$ is correct explanation of the assertion.
- ✓
Both $A$ and $R$ are true, but $R$ is not the correct explanation of the assertion.
- C
$A$ is true, but $R$ is false.
- D
$A$ is false, but $R$ is true.
AnswerCorrect option: B. Both $A$ and $R$ are true, but $R$ is not the correct explanation of the assertion.
The wires are parallel to each other but the direction of current in it is in same direction, so they attract each other. If the current in the wires is in opposite directions, then wires repel each other. When the currents are in opposite directions, the magnetic forces are reversed and the wires repels each other.
View full question & answer→MCQ 31 Mark
For two statements are given $-$ one labelled Assertion $(A)$ and the other labelled Reason $(R).$ Select the correct answer to these questions from the codes $\ce{(a), (b), (c)}$ and $(d)$ as given below :
Assertion : A moving coil galvanometer is based on magnetic effect of current.
Reason : On heating, the coil starts to rotate in direction of moving coil galvanometer.
- A
Both $A$ and $R$ are true, and $R$ is correct explanation of the assertion.
- B
Both $A$ and $R$ are true, but $R$ is not the correct explanation of the assertion.
- ✓
$A$ is true, but $R$ is false.
- D
$A$ is false, but $R$ is true.
AnswerCorrect option: C. $A$ is true, but $R$ is false.
A moving coil galvanometer is based on magnetic effect of current. A force acts on every side of the coil due to magnetic field when current is passed through the coil. Due to these forces, a couple is exerted on the coil.
View full question & answer→MCQ 41 Mark
For two statements are given $-$ one labelled Assertion $(A)$ and the other labelled Reason $(R).$ Select the correct answer to these questions from the codes $\ce{(a), (b), (c)}$ and $(d)$ as given below :
Assertion : When a charged particle moves perpendicular to magnetic field then its kinetic energy and momentum gets affected.
Reason : Force does not change velocity of charged particle.
- A
Both $A$ and $R$ are true, and $R$ is correct explanation of the assertion.
- B
Both $A$ and $R$ are true, but $R$ is not the correct explanation of the assertion.
- C
$A$ is true, but $R$ is false.
- ✓
$A$ is false, but $R$ is true.
AnswerCorrect option: D. $A$ is false, but $R$ is true.
When a charged particle moves perpendicular to magnetic field, it experiences a force which changes the direction of motion of the particle without changing the magnitude of velocity of the particle. Hence, kinetic energy remains constant but momentum of electron changes.
View full question & answer→MCQ 51 Mark
For two statements are given $-$ one labelled Assertion $(A)$ and the other labelled Reason $(R)$. Select the correct answer to these questions from the codes $\ce{(a), (b), (c)}$ and $(d)$ as given below :
Assertion : Magnetic field interacts with a moving charge and not with a stationary charge.
Reason : A moving charge produces a magnetic field.
- ✓
Both $A$ and $R$ are true, and $R$ is correct explanation of the assertion.
- B
Both $A$ and $R$ are true, but $R$ is not the correct explanation of the assertion.
- C
$A$ is true, but $R$ is false.
- D
$A$ is false, but $R$ is true.
AnswerCorrect option: A. Both $A$ and $R$ are true, and $R$ is correct explanation of the assertion.
An electric current is equivalent to the charges $($or electrons$)$ in motion. Such charges produce magnetic interaction. The magnetic field produced by current interacts with magnetic needle and deflects it.
View full question & answer→MCQ 61 Mark
For two statements are given $-$ one labelled Assertion $(A)$ and the other labelled Reason $(R)$. Select the correct answer to these questions from the codes $\ce{(a), (b), (c)}$ and $(d)$ as given below :
Assertion : The magnetic field produced by a current carrying solenoid is independent of its length and cross-sectional area.
Reason : The magnetic field inside the solenoid is uniform.
- A
Both $A$ and $R$ are true, and $R$ is correct explanation of the assertion.
- ✓
Both $A$ and $R$ are true, but $R$ is not the correct explanation of the assertion.
- C
$A$ is true, but $R$ is false.
- D
$A$ is false, but $R$ is true.
AnswerCorrect option: B. Both $A$ and $R$ are true, but $R$ is not the correct explanation of the assertion.
View full question & answer→MCQ 71 Mark
In the followin questions, a statement of Assertion is given by to corresponding statement of Reason. Of the statement mark the correct answer as :
Assertion : An electric current produced in a closed circuit by changing magnetic field is called induced current.
Reason : The direction of induced current is given by Fleming's right hand rule.
- A
If both Assertion and Reason are true and Reason is the correct explanation of Assertion.
- ✓
If both Assertion and Reason are true, but Reason is not the correct explanation of Assertion.
- C
If Assertion is true, but Reason is false.
- D
If Assertion is false, but Reason is true.
AnswerCorrect option: B. If both Assertion and Reason are true, but Reason is not the correct explanation of Assertion.
The phenomenon of generation of an electric current in a closed circuit from magnetic effects $1$ .e. by changing the magnetic field is called electromagnetic induction. The potential difference set in the circuit due to induced current is called induced emf.
It can be used to determine the direction of current in a generator's windings. When a conductor such as a wire attached to a circuit moves through a magnetic field, an electric current is induced in the wire due to Faraday's law of induction. Fleming's right $-$ hand rule gives which direction the current flows.
View full question & answer→MCQ 81 Mark
In the followin questions, a statement of Assertion is given by to corresponding statement of Reason. Of the statement mark the correct answer as :
Assertion : To avoid risk of electrical shock, the metal body of electric appliances is earthed.
Reason : Earthing saves us from electrical shocks.
- ✓
If both Assertion and Reason are true and Reason is the correct explanation of Assertion.
- B
If both Assertion and Reason are true, but Reason is not the correct explanation of Assertion.
- C
If Assertion is true, but Reason is false.
- D
If Assertion is false, but Reason is true.
AnswerCorrect option: A. If both Assertion and Reason are true and Reason is the correct explanation of Assertion.
To avoid the risk of electric shock metal body of an electric appliances is earthed. This is used as safety measure especially for those appliance that have metallic body for example electric iron, toaster etc. The metallic body is connected to low resistance conducting path for current.
View full question & answer→MCQ 91 Mark
For two statements are given $-$ one labelled Assertion $(A)$ and the other labelled Reason $(R)$. Select the correct answer to these questions from the codes $\ce{(a), (b), (c)}$ and $(d)$ as given below :
Assertion : No net force acts on a rectangular coil carrying a steady current when suspended freely in a uniform magnetic field.
Reason : Forces acting on each pair of the opposite sides of the coil are equal and opposite.
- ✓
Both $A$ and $R$ are true, and $R$ is correct explanation of the assertion.
- B
Both $A$ and $R$ are true, but $R$ is not the correct explanation of the assertion.
- C
$A$ is true, but $R$ is false.
- D
$A$ is false, but $R$ is true.
AnswerCorrect option: A. Both $A$ and $R$ are true, and $R$ is correct explanation of the assertion.
In a rectangular coil carrying a steady current, the direction of current in opposite sides of coil is opposite to each other, therefore, forces acting on each pair of the opposite sides of the coil are equal and opposite, i.e., net force on the coil is equal to zero.
View full question & answer→MCQ 101 Mark
For two statements are given $-$ one labelled Assertion $(A)$ and the other labelled Reason $(R)$. Select the correct answer to these questions from the codes $\ce{(a), (b), (c)}$ and $(d)$ as given below :
Assertion : Force experienced by moving charge will be maximum if direction of velocity of charge is parallel to applied magnetic field.
Reason : Force on moving charge is depends on direction of applied magnetic field.
- A
Both $A$ and $R$ are true, and $R$ is correct explanation of the assertion.
- B
Both $A$ and $R$ are true, but $R$ is not the correct explanation of the assertion.
- C
$A$ is true, but $R$ is false.
- ✓
$A$ is false, but $R$ is true.
AnswerCorrect option: D. $A$ is false, but $R$ is true.
Force on moving charge will be maximum if direction of velocity of charge is perpendicular to direction of magnetic field.
View full question & answer→MCQ 111 Mark
For two statements are given $-$ one labelled Assertion $(A)$ and the other labelled Reason $(R).$ Select the correct answer to these questions from the codes $\ce{(a), (b), (c)}$ and $(d)$ as given below :
Assertion : For a point on the axis of a circular coil carrying current, magnetic field is maximum at the center of the coil.
Reason : Magnetic field is proportional to the distance of point from the circular coil.
- A
Both $A$ and $R$ are true, and $R$ is correct explanation of the assertion.
- B
Both $A$ and $R$ are true, but $R$ is not the correct explanation of the assertion.
- ✓
$A$ is true, but $R$ is false.
- D
$A$ is false, but $R$ is true.
AnswerCorrect option: C. $A$ is true, but $R$ is false.
The magnitude of magnetic field produced by a current carrying circular coil is maximum at the center and is not proportional to the distance of a point from the circular coil.
View full question & answer→MCQ 121 Mark
For two statements are given $-$ one labelled Assertion $(A)$ and the other labelled Reason $(R).$ Select the correct answer to these questions from the codes $\ce{(a), (b), (c)}$ and $(d)$ as given below:
Assertion : The direction of force is given by Fleming's left $-$ hand rule.
Reason : A magnetic field exert a force on a moving charge in the same direction as the direction of field itself.
- A
Both $A$ and $R$ are true, and $R$ is correct explanation of the assertion.
- B
Both $A$ and $R$ are true, but $R$ is not the correct explanation of the assertion.
- ✓
$A$ is true, but $R$ is false.
- D
$A$ is false, but $R$ is true.
AnswerCorrect option: C. $A$ is true, but $R$ is false.
According to Fleming's left $-$ hand rule, the direction of the magnetic force on a moving charge is always perpendicular to the magnetic field.
View full question & answer→MCQ 131 Mark
For two statements are given $-$ one labelled Assertion $(A)$ and the other labelled Reason $(R)$. Select the correct answer to these questions from the codes $\ce{(a), (b), (c)}$ and $(d)$ as given below:
Assertion : A solenoid tends to expand, when a current passes through it.
Reason : Two straight parallel metallic wires carrying current in same direction attract each other.
- A
Both $A$ and $R$ are true, and $R$ is correct explanation of the assertion.
- B
Both $A$ and $R$ are true, but $R$ is not the correct explanation of the assertion.
- C
$A$ is true, but $R$ is false.
- ✓
$A$ is false, but $R$ is true.
AnswerCorrect option: D. $A$ is false, but $R$ is true.
When current flows through a solenoid, the currents in the various turns of the solenoid are parallel and in the same direction. Since the currents flowing through parallel wires in the same direction lead to a force of attraction between them, the turns of the solenoid will also attract each other and as a result, the solenoid tends to contract.
View full question & answer→MCQ 141 Mark
For two statements are given $-$ one labelled Assertion $(A)$ and the other labelled Reason $(R).$ Select the correct answer to these questions from the codes $\ce{(a), (b), (c)}$ and $(d)$ as given below :
Assertion : The magnetic field intensity at the center of a circular coil carrying current changes, if the current through the coil is doubled.
Reason : The magnetic field intensity is dependent on current in conductor.
- ✓
Both $A$ and $R$ are true, and $R$ is correct explanation of the assertion.
- B
Both $A$ and $R$ are true, but $R$ is not the correct explanation of the assertion.
- C
$A$ is true, but $R$ is false.
- D
$A$ is false, but $R$ is true.
AnswerCorrect option: A. Both $A$ and $R$ are true, and $R$ is correct explanation of the assertion.
The magnetic field at the center of circular coil is directly proportional to the current flowing through it. So if current through coil is doubled then magnetic field becomes double.
View full question & answer→MCQ 151 Mark
For two statements are given-one labelled Assertion $(A)$ and the other labelled Reason $(R)$. Select the correct answer to these questions from the codes $\ce{(a), (b), (c)}$ and $(d)$ as given below :
Assertion : Magnetic field lines show the direction $($at every point$)$ along which a small magnetised needle aligns $($at the point$).$
Reason : Magnetic field lines certainly represent the direction of magnetic field, but not the direction of force, this is because force is always perpendicular to magnetic field $B.$
- A
Both $A$ and $R$ are true, and $R$ is correct explanation of the assertion.
- ✓
Both $A$ and $R$ are true, but $R$ is not the correct explanation of the assertion.
- C
$A$ is true, but $R$ is false.
- D
$A$ is false, but $R$ is true.
AnswerCorrect option: B. Both $A$ and $R$ are true, but $R$ is not the correct explanation of the assertion.
View full question & answer→MCQ 161 Mark
For two statements are given $-$ one labelled Assertion $(A)$ and the other labelled Reason $(R)$. Select the correct answer to these questions from the codes $\ce{(a), (b), (c)}$ and $(d)$ as given below :
Assertion : Magnetic field lines forms closed loops in nature.
Reason : Mono $-$ magnetic pole does not exist in nature.
- ✓
Both $A$ and $R$ are true, and $R$ is correct explanation of the assertion.
- B
Both $A$ and $R$ are true, but $R$ is not the correct explanation of the assertion.
- C
$A$ is true, but $R$ is false.
- D
$A$ is false, but $R$ is true.
AnswerCorrect option: A. Both $A$ and $R$ are true, and $R$ is correct explanation of the assertion.
The magnetic field lines form closed loops, unlike electrostatic field lines which originate from the charge and end at charge. Mono $-$ magnetic pole does not exist in nature.
View full question & answer→MCQ 171 Mark
In the followin questions, a statement of Assertion is given by to corresponding statement of Reason. Of the statement mark the correct answer as :
Assertion : In an $AC$ generator slip $-$ rings type of commutator is used.
Reason : Slip $-$ rings are full rings with which the ends of coil are in contact.
- A
If both Assertion and Reason are true and Reason is the correct explanation of Assertion.
- ✓
If both Assertion and Reason are true, but Reason is not the correct explanation of Assertion.
- C
If Assertion is true, but Reason is false.
- D
If Assertion is false, but Reason is true.
AnswerCorrect option: B. If both Assertion and Reason are true, but Reason is not the correct explanation of Assertion.
The two parts $S_1$ and $S_2$ of the split ring are used to act as a commutator to reverse the direction of current in the coil, so they are called the split ring commutator. So, slip rings are used with simple $a.c.$ generators, whereas a commutator is used with $d.c.$ motors.
View full question & answer→