MCQ 1011 Mark
The material of permanent magnet has
- A
High retentivity, low coercivity
- B
Low retentivity, high coercivity
- C
Low retentivity, low coercivity
- ✓
High retentivity, high coercivity
AnswerCorrect option: D. High retentivity, high coercivity
High retentivity, high coercivity
View full question & answer→MCQ 1021 Mark
The permanent magnet is made from which one of the following substances
MCQ 1031 Mark
Temperature above which a ferromagnetic substance becomes paramagnetic is called
MCQ 1041 Mark
When a magnetic substance is heated, then it
- A
- ✓
- C
Does not effect the magnetism
- D
View full question & answer→MCQ 1051 Mark
Two identical bar magnets are placed on above the other such that they are mutually perpendicular and bisect each other. The time period of this combination in a horizontal magnetic field is T. The time period of each magnet in the same field is
- A
$\sqrt 2$T
- B
$2^{1/4}$T
- ✓
$2^{-1/4}$T
- D
$2^{-1/2}$T
AnswerCorrect option: C. $2^{-1/4}$T
(c) $2^{-1/4}$T
View full question & answer→MCQ 1061 Mark
A magnet oscillating in a horizontal plane has a time period of 2 second at a place where the angle of dip is $30^{\circ}$ and 3 seconds at another place where the angle of dip is $60^{\circ}$. The ratio of resultant magnetic fields at the two places is
- A
$\frac{4\sqrt 3}{7}$
- B
$\frac{4}{9\sqrt 3}$
- ✓
$\frac{9}{4\sqrt 3}$
- D
$\frac{9}{\sqrt 3}$
AnswerCorrect option: C. $\frac{9}{4\sqrt 3}$
(c) $\frac{9}{4\sqrt 3}$
View full question & answer→MCQ 1071 Mark
The length of a magnet is large compared to its width and breadth. The time period of its oscillation in a vibration magnetometer is 2 s. The magnet is cut along its length into three equal parts and three parts are then placed on each other with their like poles together. The time period of this combination will be
MCQ 1081 Mark
A bar magnet is oscillating in the earth's magnetic field with time period T. If its mass is increased four times then its time period will be
MCQ 1091 Mark
A thin rectangular magnet suspended freely has a period of oscillation equal to T. Now it is broken into two equal halves (each having half of the original length) and one piece is made to oscillate freely in the same field. If its period of oscillation is T ¢, then ratio $\frac{\mathrm{T}^{\prime}}{\mathrm{T}}$ is
- A
$\frac{1}{4}$
- B
$\frac{1}{2\sqrt 2}$
- ✓
$\frac{1}{2}$
- D
AnswerCorrect option: C. $\frac{1}{2}$
(c) $\frac{1}{2}$
View full question & answer→MCQ 1101 Mark
A bar magnet is oscillating in the Earth’s magnetic field with a period T. What happens to its period and motion if its mass is quadrupled
AnswerCorrect option: A. Motion remains S.H.M. with time period = 2T
(a) Motion remains S.H.M. with time period = 2T
View full question & answer→MCQ 1111 Mark
In a tangent galvanometer a current of $0.1$ A produces a deflection of $30^\circ$. The current required to produce a deflection of $60^\circ$ is
- A
$0.2 \ A$
- ✓
$0.3 \ A$
- C
$0.4 \ A$
- D
$0.5 \ A$
AnswerCorrect option: B. $0.3 \ A$
$0.3 \ A$
View full question & answer→MCQ 1121 Mark
The magnetic needle of a tangent galvanometer is deflected at an angle $30^{\circ}$ due to a magnet. The horizontal component of earth's magnetic field $0.34 \times 10^{-4} \mathrm{~T}$ is along the plane of the coil. The magnetic intensity is
- A
$ 1.96 \times 10^{-4} \mathrm{~T} $
- ✓
$ 1.96 \times 10^{-5} \mathrm{~T} $
- C
$ 1.96 \times 10^4 \mathrm{~T} $
- D
$ 1.96 \times 10^5 \mathrm{~T}$
AnswerCorrect option: B. $ 1.96 \times 10^{-5} \mathrm{~T} $
$ 1.96 \times 10^{-5} \mathrm{~T} $
View full question & answer→MCQ 1131 Mark
When two magnetic moments are compared using equal distance method the deflections produced are $45^{\circ}$ and $30^{\circ}$. If the length of magnets are in the ratio 1 : 2, the ratio of their pole strengths is
- A
- B
- C
$\sqrt{3}: 1$
- ✓
$2\sqrt{3}: 1$
AnswerCorrect option: D. $2\sqrt{3}: 1$
(d) $2\sqrt{3}: 1$
View full question & answer→MCQ 1141 Mark
The period of oscillations of a magnet is 2 sec. When it is remagnetised so that the pole strength is 4 times its period will be
MCQ 1151 Mark
The number of turns and radius of cross-section of the coil of a tangent galvanometer are doubled. The reduction factor K will be
MCQ 1161 Mark
The time period of a vibration magnetometer is $T_0$. Its magnet is replaced by another magnet whose moment of inertia is 3 times and magnetic moment is 1/3 of the initial magnet. The time period now will be
AnswerCorrect option: A. $3 \mathrm{T}_0$
(a) $3 \mathrm{T}_0$
View full question & answer→MCQ 1171 Mark
A magnet makes $40$ oscillations per minute at a place having magnetic field intensity of $0.1 \times 10^{-5} \mathrm{~T}$. At another place, it takes $2.5 \sec$ to complete one vibration. The value of earth's horizontal field at that place is
- A
$ 0.25 \times 10^{-6} \mathrm{~T} $
- ✓
$ 0.36 \times 10^{-6} \mathrm{~T} $
- C
$ 0.66 \times 10^{-8} \mathrm{~T} $
- D
$ 1.2 \times 10^{-6} \mathrm{~T}$
AnswerCorrect option: B. $ 0.36 \times 10^{-6} \mathrm{~T} $
$ 0.36 \times 10^{-6} \mathrm{~T} $
View full question & answer→MCQ 1181 Mark
The magnet of a vibration magnetometer is heated so as to reduce its magnetic moment by 19%. By doing this the periodic time of the magnetometer will
MCQ 1191 Mark
Two short magnets having magnetic moments in the ratio 27 : 8, when placed on opposite sides of a deflection magnetometer, produce no deflection. If the distance of the weaker magnet is 0.12 m from the centre of deflection magnetometer, the distance of the stronger magnet from the centre is
MCQ 1201 Mark
The period of oscillation of a vibration magnetometer depends on which of the following factors
MCQ 1211 Mark
The bob of a simple pendulum is replaced by a magnet. The oscillations are set along the length of the magnet. A copper coil is added so that one pole of the magnet passes in and out of the coil. The coil is short-circuited. Then which one of the following happens
MCQ 1221 Mark
The time period of a freely suspended magnet is 2 sec. If it is broken in length into two equal parts and one part is suspended in the same way, then its time period will be
MCQ 1231 Mark
The period of oscillations of a magnetic needle in a magnetic field is 1.0 sec. If the length of the needle is halved by cutting it, the time period will be
MCQ 1241 Mark
When $\sqrt {3}$ ampere current is passed in a tangent galvanometer, there is a deflection of 30° in it. The deflection obtained when 3 amperes current is passed, is
View full question & answer→MCQ 1251 Mark
To measure which of the following, is a tangent galvanometer used
MCQ 1261 Mark
A short magnetic needle is pivoted in a uniform magnetic field of strength 1 T. When another magnetic field of strength $\sqrt 3 T$ is applied to the needle in a perpendicular direction, the needle deflects through an angle q, where q is
- A
$30^{\circ}$
- B
$45^{\circ}$
- C
$90^{\circ}$
- ✓
$60^{\circ}$
AnswerCorrect option: D. $60^{\circ}$
(d) $60^{\circ}$
View full question & answer→MCQ 1271 Mark
Two normal uniform magnetic field contain a magnetic needle making an angle 60° with F. Then the ratio of $\frac{F}{H}$ is
- A
- B
- C
$\sqrt 3:1$
- ✓
$1 : \sqrt 3$
AnswerCorrect option: D. $1 : \sqrt 3$
(d) $1 : \sqrt 3$
View full question & answer→MCQ 1281 Mark
A certain amount of current when flowing in a properly set tangent galvanometer, produces a deflection of 45°. If the current be reduced by a factor of $\sqrt 3$, the deflection would
View full question & answer→MCQ 1291 Mark
The strength of the magnetic field in which the magnet of a vibration magnetometer is oscillating is increased 4 times its original value. The frequency of oscillation would then become
- ✓
- B
Four times its original value
- C
- D
One-fourth its original value
View full question & answer→MCQ 1301 Mark
Using a bar magnet P, a vibration magnetometer has time period 2seconds. When a bar Q (identical to P in mass and size) is placed on top of P, the time period is unchanged. Which of the following statements is true
- A
Q is of non-magnetic material
- ✓
Q is a bar magnet identical to P, and its north pole placed on top of P's north pole
- C
Q is of unmagnetized ferromagnetic material
- D
Nothing can be said about Q's properties
AnswerCorrect option: B. Q is a bar magnet identical to P, and its north pole placed on top of P's north pole
Q is a bar magnet identical to P, and its north pole placed on top of P's north pole
View full question & answer→MCQ 1311 Mark
Two tangent galvanometers having coils of the same radius are connected in series. A current flowing in them produces deflections of 60° and 45° respectively. The ratio of the number of turns in the coils is
AnswerCorrect option: D. $\sqrt 3/1$
(d) $\sqrt 3/1$
View full question & answer→MCQ 1321 Mark
The sensitivity of a tangent galvanometer is increased if
MCQ 1331 Mark
A magnetic needle suspended by a silk thread is vibrating in the earth's magnetic field. If the temperature of the needle is increased by 500°C, then
- A
The time period decreases
- B
The time period remains unchanged
- ✓
The time period increases
- D
The needle stops vibrating
AnswerCorrect option: C. The time period increases
The time period increases
View full question & answer→MCQ 1341 Mark
Twists of suspension fibre should be removed in vibration magnetometer so that
- A
- B
- ✓
Magnet may vibrate freely
- D
Cannot be said with certainty
AnswerCorrect option: C. Magnet may vibrate freely
Magnet may vibrate freely
View full question & answer→MCQ 1351 Mark
Which of the following statement is true about magnetic moments of atoms of different elements
- A
All have a magnetic moment
- B
None has a magnetic moment
- C
All acquire a magnetic moment under external magnetic field and in same direction as the field
- ✓
None of the above statements are accurate
AnswerCorrect option: D. None of the above statements are accurate
None of the above statements are accurate
View full question & answer→MCQ 1361 Mark
The time period of a freely suspended magnet is 4 seconds. If it is broken in length into two equal parts and one part is suspended in the same way, then its time period will be
MCQ 1371 Mark
Time period in vibration magnetometer will be infinity at
MCQ 1381 Mark
Keeping dissimilar poles of two magnets of equal pole strength and length same side, their time period will be
MCQ 1391 Mark
A bar magnet has a magnetic moment equal to $5\times 10^{-5}$ weber $\times$ m. It is suspended in a magnetic field which has a magnetic induction (B) equal to $8π \times 10^{-5}$ tesla. The magnet vibrates with a period of vibration equal to 15 sec. The moment of inertia of the magnet is
- A
$22.5\times kg\times m^2$
- B
$11.25\times kg\times m^2$
- C
$5.62\times kg\times m^2$
- ✓
$7.16\times 10^{-7}kg-m^2$
AnswerCorrect option: D. $7.16\times 10^{-7}kg-m^2$
(d) $7.16\times 10^{-7}kg-m^2$
View full question & answer→MCQ 1401 Mark
Tangent galvanometer is used to measure
- ✓
- B
- C
Magnetic moments of bar magnets
- D
View full question & answer→MCQ 1411 Mark
Vibration magnetometer works on the principle of
- ✓
Torque acting on the bar magnet
- B
Force acting on the bar magnet
- C
Both the force and the torque acting on the bar magnet
- D
AnswerCorrect option: A. Torque acting on the bar magnet
Torque acting on the bar magnet
View full question & answer→MCQ 1421 Mark
A small bar magnet A oscillates in a horizontal plane with a period T at a place where the angle of dip is 60$^\circ$. When the same needle is made to oscillate in a vertical plane coinciding with the magnetic meridian, its period will be
- ✓
$\frac{T}{\sqrt 2}$
- B
- C
$\sqrt 2 T$
- D
AnswerCorrect option: A. $\frac{T}{\sqrt 2}$
(a) $\frac{T}{\sqrt 2}$
View full question & answer→MCQ 1431 Mark
Magnets A and B are geometrically similar but the magnetic moment of A is twice that of B. If $T_1$ and $T_2$ be the time periods of the oscillation when their like poles and unlike poles are kept together respectively, then $\frac{T_1}{T_2}$ will be
- A
$\frac{1}{3}$
- B
$\frac{1}{2}$
- ✓
$\frac{1}{\sqrt3}$
- D
$\sqrt3$
AnswerCorrect option: C. $\frac{1}{\sqrt3}$
(c) $\frac{1}{\sqrt3}$
View full question & answer→MCQ 1441 Mark
The time period of a bar magnet suspended horizontally in the earth's magnetic field and allowed to oscillate
- ✓
Is directly proportional to the square root of its mass
- B
Is directly proportional to its pole strength
- C
Is inversely proportional to its magnetic moment
- D
Decreases if the length increases but pole strength remains same
AnswerCorrect option: A. Is directly proportional to the square root of its mass
Is directly proportional to the square root of its mass
View full question & answer→MCQ 1451 Mark
At two places $A$ and $B$ using vibration magnetometer, a magnet vibrates in a horizontal plane and its respective periodic time are $2$ sec and $3 \sec$ and at these places the earth's horizontal components are $H_A$ and $H_B$ respectively. Then the ratio between $H_A$ and $H_B$ will be
- ✓
$9 : 4$
- B
$3 : 2$
- C
$4 : 9$
- D
$2 : 3$
AnswerCorrect option: A. $9 : 4$
$9 : 4$
View full question & answer→MCQ 1461 Mark
A magnetic needle suspended horizontally by an unspun silk fibre, oscillates in the horizontal plane because of the restoring force originating mainly from
- A
The torsion of the silk fibre
- B
- ✓
The horizontal component of earth's magnetic field
- D
AnswerCorrect option: C. The horizontal component of earth's magnetic field
The horizontal component of earth's magnetic field
View full question & answer→MCQ 1471 Mark
A magnet of magnetic moment M oscillating freely in earth's horizontal magnetic field makes n oscillations per minute. If the magnetic moment is quadrupled and the earth's field is doubled, the number of oscillations made per minute would be
- A
$\frac{n}{2\sqrt2}$
- B
$\frac{n}{\sqrt2}$
- ✓
$2\sqrt 2 n$
- D
$\sqrt 2 n$
AnswerCorrect option: C. $2\sqrt 2 n$
(c) $2\sqrt 2 n$
View full question & answer→MCQ 1481 Mark
Two magnets A and B are identical in mass, length and breadth but have different magnetic moments. In a vibration magnetometer, if the time period of B is twice the time period of A. The ratio of the magnetic moments $\mathrm{M}_{\mathrm{A}} / \mathrm{M}_{\mathrm{B}}$ of the magnets will be
View full question & answer→MCQ 1491 Mark
Two magnets are held together in a vibration magnetometer and are allowed to oscillate in the earth's magnetic field with like poles together, 12 oscillations per minute are made but for unlike poles together only 4 oscillations per minute are executed. The ratio of their magnetic moments is
MCQ 1501 Mark
A bar magnet A of magnetic moment $M_A$ is found to oscillate at a frequency twice that of magnet B of magnetic moment $M_B$ when placed in a vibrating magneto-meter. We may say that
- A
$M_A=2M_B$
- B
$M_A=8M_B$
- ✓
$M_A=4M_B$
- D
$M_B=8M_A$
AnswerCorrect option: C. $M_A=4M_B$
(c) $M_A=4M_B$
View full question & answer→