Magnetism and Matter Test 38

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Magnetism and Matter Test 38

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Weekly Quiz Competition

Question 1
1 / -0

A frog can be deviated in a magnetic field produced by a current in a vertical solenoid placed below the frog. This is possible because the body of the frog behaves as

A
$$ Paramagnetic $$

B
$$ Diamagnetic $$

C
$$ Ferromagnetic $$

D
$$ Antiferromagnetic $$

Solution

A frog can be deviated in a magnetic field produced by a current in a vertical solenoid placed below the frog. This is possible because the body of the frog behaves as diamagnetic substances because diamagnetic substances are repelled by the magnetic field.
Question 2
1 / -0

Curie-Weiss law is obeyed by iron at a temperature ......

A
Below Curie temperature

B
Above Curie temperature

C
At Curie temperature only

D
At all temperatures

Solution

Curie-Weiss law is obeyed by iron at a temperature above its curie temperature.
Question 3
1 / -0

The magnetic susceptibility of any paramagnetic material changes with absolute temperature T as

A
Directly proportional to T

B
Remains constant

C
Inversely proportional to T

D
Exponentially decaying with T

Solution

The magnetic susceptibility of any paramagnetic material changes with absolute temperature $$T$$ as it is inversely proportional to $$T$$.
Question 4
1 / -0

A superconductor exhibits perfect

A
$$ Ferrimagnetism $$

B
$$ Ferromagnetism $$

C
$$ Paramagnetism $$

D
$$ Diamagnetism $$

Solution

A superconductor exhibits perfect diamagnetism.
Question 5
1 / -0

Which of the following is diamagnetism

A
$$ Aluminium $$

B
$$ Quartz $$

C
$$ Nickel $$

D
$$ Bismuth $$

Solution

Bismuth is diamagnetism.
Question 6
1 / -0

The resistance in the following circuit is increased at a particular instant. At this instant the value of resistance is $$10 \Omega$$. The current in the circuit will be now

A
$$i = 0.5 \,A$$

B
$$i > 0.5 \,A$$

C
$$i < 0.5 \,A$$

D
$$i = 0$$

Solution

If resistance is constant $$(10\Omega)$$ then steady current in the circuit $$i = \dfrac{5}{10} = 0.5 \,A.$$ But resistance is increasing it means current through the circuit start decreasing. Hence inductance comes in picture which induces a current in the circuit in the same direction of main current.So $$i > 0.5 \,A.$$
Question 7
1 / -0

The current through a $$4.6\, H$$ inductor is shown in the following graph. The induced emf during the time interval $$t = 5$$ milli-sec to $$6$$ milli-sec will be

A
$$10 \,V$$

B
$$-23 \times 10^3 \,V$$

C
$$23 \times 10^3 \,V$$

D
Zero

Solution

Rate of decay of current between $$t = 5$$ ms to $$6$$ ms
$$= \dfrac{di}{dt} = -$$ (Slope of the line BC)
$$= - \left ( \dfrac{5}{1 \times 10^{-3}} \right ) = -5 \times 10^3 \,A / s.$$

Hence induced emf
$$e = -L \dfrac{di}{dt} = -4.6 \times (-5 \times 10^3) = 23 \times 10^3 \,V.$$
Question 8
1 / -0

A horizontal loop abcd is moved across the pole pieces of a magnet as shown in fig. with a constant speed v. When the edge ab of the loop enters the pole pieces at time $$t = 0$$ sec. Which one of the following graphs represents correctly the induced emf in the coil

A

B

C

D

Solution

When loop enters in field between the pole pieces, flux linked with the coil first increases (constantly) so a constant emf induces, when coil entered completely within the field, no flux change so $$e = 0.$$
When coil exit out, flux linked with the coil decreases, hence again emf induces, but in opposite direction.
Question 9
1 / -0

For previous objective, which of the following graphs is correct

A

B

C

D

Solution

If at any instant, current through the circuit is i then applying Kirchoffs voltage law, $$iR + e = E \Rightarrow e = E - iR.$$ Therefore,graph between e and i will be a straight line having negative slope and having a positive intercept.
Question 10
1 / -0

The variation of magnetic susceptibility $$ (\chi) $$ with magnetising field for a paramagnetic substance is

A

B

C

D

Solution

Susceptibility of a paramagnetic substance is independent of magnetising field.