Magnetism and Matter Test 45

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Magnetism and Matter Test 45

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Weekly Quiz Competition

Question 1
1 / -0

Which of the following magnetic line alignment is correct for ferrimagnetism?

A
$$\uparrow, \uparrow, \uparrow, \downarrow, \downarrow$$

B
$$\uparrow, \uparrow, \uparrow, \uparrow$$

C
$$\uparrow, \downarrow, \uparrow, \downarrow$$

D
$$\downarrow, \downarrow, \downarrow, \downarrow$$

Solution
Question 2
1 / -0

The mass of a specimen of a ferromagnetic material is 0.6 kg and the density is $$7.8 \times {10^3}\;{\text{kg}}\;{{\text{m}}^{{\text{ - 3}}}}$$ . If the area of the hysteresis loop of the alternating magnetizing field of frequency 50 Hz is 0.722 MKS units, then hysteresis loss per second will be

A
$$27.77 \times {10^{ - 5}}{\text{J}}$$

B
$$2.777 \times {10^{ - 5}}{\text{J}}$$

C
$$27.77 \times {10^{ - 4}}{\text{J}}$$

D
$$27.77 \times {10^{ - 6}}{\text{J}}$$

Solution
Question 3
1 / -0

A coil of 50 turns and area $$1.25 \times {10^{ - 3}}{{\text{m}}^{\text{2}}}$$ is pivoted about a vertical diameter in a uniform current of the horizontal magnetic field and carries a current of 2A. When the coil is held with its plane in N-S direction, it experiences a couple of 0.04 N-m; and when its plane is E-W, the corresponding couple is 0.03 N-m. The magnetic induction is

A
0.2 T

B
0.3 T

C
0.4 T

D
0.5 T

Solution
Question 4
1 / -0

An electron moves on a staight line path $$XY$$ as shown. The abcd is a coil adjacent to the path of electron. What will be the direction of current, if any,induced in the coil?

A
No current induced

B
abcd

C
adcb

D
The current will reverse its direction as the electron goes past the coil

Solution
Question 5
1 / -0

A uniform but time varying magnetic field exists in cylindrical region and directed into the appear. If field decreases with time and a positive charge placed at any point inside the region, then if moves

A
along 1

B
along 2

C
along 3

D
along 4

Solution

As magnetic field is decreasing so induced electric field should be in this way so that it will increase magnetic field through loop so current will flow clockwise if positively charged is placed as some point it will move clockwise or in direction showing by arrow 4.
Question 6
1 / -0

A coil having n turns and resistance $$R\Omega$$, is connected in series with resistance $$R$$. This combination is moved in time t seconds from a magnetic field $$W_{1}$$ weber to $$W_{2}$$ weber. The induced current in the circuit is

A
$$- \frac{W_{2} - W_{1}}{5Rnt}$$

B
$$- \frac{W_{2} - W_{1}}{5Rt}$$

C
$$- \frac{W_{2} - W_{1}}{Rnt}$$

D
$$- \frac{n(W_{2} - W_{1})}{5Rt}$$

Solution
Question 7
1 / -0

Choose the correct examples for the ferro magnetic material.

A
Aluminum

B
Copper

C
Steel

D
Cobalt

Solution
Question 8
1 / -0

A bar magnet is demagnetized by inserting it inside a solenoid of length 0.2 m, 100 turns, and carrying a curent of 5.2 A. The coercivity of the bar magnet is:

A
2600 A/m

B
520 A/m

C
285 A/m

D
1200 A/m

Solution

$$\textbf{Given}$$:Length of solenoid l = 0.2 m
No. of turns N = 100
Current I = 5.2 A
$$\textbf{To find}$$ : Coercivity of bar magnet H

$$\textbf{Solution}$$ :
Coercivity of bar magnet H = nI
Now, n = $$\dfrac{N}{l}$$
Therefore, H = $$\dfrac{N}{l}\times{I}$$ = $$\dfrac{100}{0.2}\times{5.2}$$ = 26$$\times{100}$$ = 2600
H = 2600 A/m

$$\textbf{Hence A is the correct option}$$
Question 9
1 / -0

A small piece of metal $$\left( { \mu }_{ r }=20 \right) $$ of volume $$10 c{ m }^{ 2 }$$ has a uniform magnetic field 4 T inside it. The magnetic energy stored in the metal is:

A
3.18 J

B
5.64 J

C
6.36 J

D
1.59 J

Solution
Question 10
1 / -0

A conducting circular loop made of a thin wire, has area $$3.5\times 10^{ -3 }m^{ 2 }$$ and resistance 10 $$\Omega $$. It is placed perpendicular to a time dependent magnetic field B(t)=(0.4T)sin(50$$\pi $$t). The field is uniform in space. Then the net charge flowing through the loop during t=0 s and t=10 ms is close to :

A
0.07 mC

B
0.21 mC

C
0.14 mC

D
0.06 mC

Solution