Physics Test 199

Result

Physics Test 199

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Weekly Quiz Competition

Question 1
4 / -1

A current loop in a magnetic field

A
can be in equilibrium in two orientations, both the equilibrium states are unstable

B
can be in equilibrium in two orientations, one stable while the other is unstable.

C
experiences a torque whether the field is uniform or non uniform in all orientations.

D
can be in equilibrium in one orientation.

Solution
Question 2
4 / -1

A compass needle which is allowed to move in a horizontal plane is taken to a geomagnetic pole. It

A
will become rigid showing no movement

B
will stay in any position

C
will stay in north-south direction only

D
will stay in east-west direction only

Solution

A compass needle which is allowed to move in a horizontal plane is taken to a geomagnetic pole. It will stay in any position as the horizontal component of earth’s magnetic field becomes zero at the geomagnetic pole.
Question 3
4 / -1

A bar magnet of magnetic moment M is placed at right angles to a magnetic induction B. If a force F is experienced by each pole of the magnet, the length of the magnet will be

A
MB / F

B
BF / M

C
MF / B

D
F / MB

Solution
Question 4
4 / -1

Electromagnets are made of soft iron because soft iron has

A
low retentivity and high coercive force

B
high retentivity and high coercive force

C
low retentivity and low coercive force

D
high retentivity and low coercive force

Solution

Electromagnets are made of soft iron because soft iron has low retentivity and low coercive force or low coercivity. Soft iron is a soft magnetic material.
Question 5
4 / -1

A short bar magnet of magnetic moment 0.4JT⁻¹ is placed in a uniform magnetic field of 0.16 T. The magnet is in stable equilibrium when the potential energy is

A
0.064 J

B
-0.064 J

C
zero

D
-0.082 J

Solution
Question 6
4 / -1

A battery of internal resistance 2 Ω is connected to a variable resistor whose value can vary from 4 Ω to 10 Ω .The resistance is initially set at 4 Ω. If the resistance is now increased then

A
power consumed by it will decrease.

B
power consumed by it will increase.

C
power consumed by it may increase or may decrease.

D
power consumed will first increase then decrease.

Solution

Power maximum when r = R. So, the power consumed by it will decrease when we increase the load resistance for R > rR > r.
Question 7
4 / -1

The maximum current that can be measured by a galvanometer of resistance 40 Ω is 10 mA. It is converted into a voltmeter that can read upto 50 V. The resistance to be connected is series with the galvanometer (in ohm) is

A
2010

B
4050

C
5040

D
4960

Solution

To convert galvanometer into voltmeter, the necessary value of resistance to be connected in series with the galvanometer is
Question 8
4 / -1

Two identical bar magnets are fixed with their centres a ta distance d apart. A stationary charge Q is placed at P in between the gap of the two magnets at a distance D from the centre O as shown in the figure

A
zero

B
directed along OP

C
directed along PO

D
directed perpendicular to the plane of paper

Solution

Magnetic field due to bar magnets exerts force on moving charges only. Since the charge is at rest, zero force acts on it.
Question 9
4 / -1

A bar magnet having a magnetic moment of 2×10⁴JT⁻¹ is free to rotate in a horizontal plane. A horizontal magnetic field B = 6×10⁻⁴T exists in the space. The work done in taking the magnet slowly from a direction parallel to the field to a direction 60° from the field is

A
12 J

B
6 J

C
2 J

D
0.6 J

Solution
Question 10
4 / -1

Nickel shows ferromagnetic property at room temperature. If the temperature is increased beyond Curie temperature, then it will show

A
anti ferromagnetism

B
no magnetic property

C
diamagnetism

D
paramagnetism

Solution

Above Curie temperature, ferromagnetic material become paramagnetic.