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OTI365 - NTSE - X Standard
NTSE SAT Physics - Magnetic Effects of Electric Current Important Questions

SAT Physics - Magnetic Effects of Electric Current

Exam Duration: 45 Mins Total Questions : 30

1 )

The magnetic lines of force, inside a current carrying solenoid are

(a)
perpendicular to the axis and equidistance from each other
(b)
circular and they do not intersect each other
(c)
along the axis and parallel to each other
(d)
circular at the ends but are parallel to the axis

2 )

Magnetic lines of force

(a)
form closed circuits
(b)
cannot intersect
(c)
are crowded together near the poles
(d)
all the above

3 )

If the current passing through a conductor is doubled then the heat produced becomes

(a)
4 times
(b)
2 times
(c)
8 times
(d)
remains same

4 )

The force between two parallel wires carrying current has been used to define

(a)
ampere
(b)
volt
(c)
coulomb
(d)
watts

5 )

An electric current passes through a straight wire in the direction of south to north. Magnetic compasses are placed at points A and B as shown in the figure.

What is your observation?

(a)
The needle will not deflect
(b)
Only one of the needles will deflect
(c)
Both the needles will deflect in the same direction
(d)
The needles will deflect in the opposite directions

6 )

Which of the following devices works on the principle of electromagnetic induction?

(a)
Ammeter
(b)
Voltmeter
(c)
Generator
(d)
Galvanometer

7 )

Which of the following describes the common domestic power supplied in India?

(a)
220 V, 100 Hz
(b)
220 V, 50 Hz
(c)
110 V, 100 Hz
(d)
100 V, 50 Hz

8 )

Kilowatt-hour is the unit of

(a)
Potential difference
(b)
Electric power
(c)
Electrical energy
(d)
Charge

9 )

The magnetic field produced at the center of a circular wire is proportional to ____ and inversely proportional to _____

(a)
Radius of loop, current
(b)
Current, radius of loop
(c)
Length of conductor, current
(d)
Weight of conductor, current

10 )

The insulation cover on the earth wire is ____

(a)
Red
(b)
Black
(c)
Green
(d)
White

11 )

Magnetic lines of force inside a solenoid are:

(a)
From N to S
(b)
From S to N
(c)
Circular
(d)
Interest one another

12 )

When current is circular, the associated magnetic field is

(a)
Straight
(b)
Elliptical
(c)
Circular
(d)
Parabolic.

13 )

When current flows clockwise in a loop, the polarity of its face is

(a)
East
(b)
South
(c)
West
(d)
North

14 )

When current flow anticlockwise in a loop the magnetic polarity of the face is

(a)
East
(b)
South
(c)
West
(d)
North

15 )

For a solenoid carrying a current I and having n turns per unit length, wrapped on a core of permeability μ, the correct expression for magnetic field intensity (b) is

(a)
B=\(\frac { { \mu }_{ 0 } }{ \mu } nI\)
(b)
\(\frac { { \mu }_{ 0 }\mu I }{ n } \)
(c)
B=μ₀μnI
(d)
B=\(\frac { { \mu }_{ 0 }\mu n }{ I } \)

16 )

In a three pin socket (shoe) the bigger hole is connected to

(a)
Any wire
(b)
Live wire
(c)
Neutral wire
(d)
Earth wire

17 )

Which of the following correctly describes the magnetic field near a long straight wire?

(a)
The field consists of straight lines perpendicular to the wire
(b)
The field consists of straight lines parallel to the wire.
(c)
The field consists of radial lines originating from the wire.
(d)
The field consists of concentric circles centred on the wire.

18 )

An electron enters a magnetic field at right angles to it as shown in figure. The direction of force acting on the electron will be

(a)
To the right
(b)
To the left
(c)
Out of the page
(d)
Into the page.

19 )

A magnetic field exerts no force on:

(a)
An electric charge moving perpendicular to its direction
(b)
an unmagnetised iron bar
(c)
a stationary electric charge
(d)
a magnet

20 )

Which of the following instruments works by electromagnetic induction?

(a)
telephone receiver
(b)
simple motor
(c)
dynamo
(d)
moving coil galvanometer.

21 )

The magnetic field lines inside a current carrying solenoid are:

(a)
along the axis and parallel to each other
(b)
perpendicular to the axis and equidistant from each other
(c)
circular and they do not intersect each other
(d)
circular at the ends but they are parallel to the axis inside the solenoid

22 )

At the time of short circuit, the current in the circuit:

(a)
Vary continuously
(b)
Reduces considerably
(c)
Increases heavily
(d)
does not change.

23 )

Current flowing in conductor A is 2A and current flowing in conductor B is 4A. The ratio of magnetic field produced around conductor A to the magnetic field produced around conductor B at a distance 10 cm from both the conductors is:

(a)
2:1
(b)
1:2
(c)
4:1
(d)
√2:1

24 )

The direction of the magnetic field at a point P above the current carrying wire is

(a)
Down the page
(b)
Up the page
(c)
Into the page
(d)
Out of the page.

25 )

If the plug of the key is taken out (i.e. the circuit is made open) and magnetic field lines are drawn over the horizontal plane white sheet of paper, the lines are:

(a)
Concentric circles
(b)
Elliptical in shape
(c)
Straight lines parallel to. each other
(d)
Parabolic in shape

26 )

A charged particle moving in a magnetic field experience a maximum force, when it moves at right angle to the direction of magnetic field. However, a student observes that a charged particle moving in the region of a magnetic field experiences no force and continues to move in a straight line. The observation of the student is correct only if:

(a)
Charged particle moves at an angle 30° with the magnetic field
(b)
Charged particle moves at an angle of 60 with the magnetic field
(c)
Charged particle either moves parallel or antiparallel to the magnetic field
(d)
Charged particle can never move in a straight line in the magnetic field.

27 )

A conductor of length I is moved perpendicular to uniform magnetic field B with velocity V as shown in figure.

(a)
zero
(b)
BIV
(c)
BIV/2
(d)
BI²V/2

28 )

The mutual inductance between two coils depends o

(a)
Medium between the coils only
(b)
Separation between two coils only
(c)
Both a and (b)
(d)
None of (a) and (b)

29 )

Two identical circular loops of metal wire are lying on a able without touching each other. Loop-A carries a current, which increases with time. In response, loop-B