ECAT MCQ Quiz Hub

1. Magnetic force acting on a unit positive charge moving perpendicular to the magnetic field with a unit velocity is called
magnetic flux
magnetic field intensity
magnetic induction
self inductance

2. A current carrying conductor is placed in a uniform magnetic field parallel to it. The magnetic force experienced by the conductor is
F=1/B
F=1/Bsin?
F/0
F=1/Bcos?

3. What is the value of the current in a wire of 10cm long at the right angle to a uniform magnetic field of 0.5 Weber/m2 when the force acting on the wire is 5N?
1A
10A
100A
1000A

4. When a particle of charge q and mass m enters into a uniform magnetic field B moving with a velocity v perpendicular to the direction for the field it describes a circular path of radius
R=qB/mV
R=mV/qB
R=qmV/B
R=qmB/V

5. Two parallel wires carrying currents in the opposite directions
repel each other
attract each other
have no effect upon each other
they cancel out their individual magnetic fields

6. A magnetic compass will be deflected if it is kept near a
charge in motion
charge at rest
both
none

7. A magnetic field
always exerts a force on a charged particle
never exerts a force on a charged particles
exerts a force if the charged particle is moving in the direction of the magnetic field lines
exerts a force if the charged particle is moving perpendicular to the magnetic field lines

8. A moving coil galvanometer of resistance 100? gives half scale deflection for a current of 20mA. What will be the potential difference across it?
4 volt
5 volt
2 volt
0.4 volt

9. Which one of the following material is most suitable for making core of an electromagnet?
air
steel
Cu-Ni alloy
soft iron

10. The magnetic force experienced by a charge particle moving in a magnetic field will be minimum when it moves
perpendicular to the field
parallel to the field
inclined parallel to the field
at an angle of 45?

11. The relationship between Tesla and smaller unit Gauss of magnetic induction is given by
1T = 103 G
1T = 10-4 G
1T = 10-2 G
1T = 104 G

12. If the plane of the rectangular coil is parallel to the magnetic field (i.e radial magnetic field) the torque on the coil is
? = NIAB cos?
? = NIAB sin?
? = NIAB tan?
? = NIAB

13. Magnetic flux and flux density are related by
magnetic flux = flux density / area
magnetic flux = flux density x area
flux density = magnetic flux area
flux density = magnetic flux x area

14. The standard vector symbol for flux density is
M
L
H
B

15. The charged particle enters the uniform magnetic field in such a way that its initial velocity is not perpendicular to the field the orbit will be
a circle
a spiral
an ellipse
helix

16. An electron enters a region where the electric field E is perpendicular to the magnetic field B. It will suffer no deflection if
E = BeV
B = eE/V
E = BV
E = BeV/2

17. Value of permeability of tree space in SI units is
4?x10-9 WbA-1m-1
4?x10-7 WbA-1m-1
4?x10-10 WbA-1m-1
4?x10-8 WbA-1m-1

18. The magnetic field strength of solenoid is
B = ??NI
B = ??N/I
B = ??nI
both (b) and C

19. An instrument which can measure potential without drawing any current is
voltmeter
galvanometer
cathode ray oscilloscope (CRO)
ammeter

20. The deflection for 50 division of galvanometer is decreased to 25 divisions by shunt resistance of 12?. Galvanometer resistance is
18?
30?
24?
12?

21. When the coil of the galvanometer is in equilibrium then the deflecting couple is
zero
equal to the restoring couple
greater than the restoring couple
smaller than the restoring couple

22. The sensitivity of a galvanometer is given by
C/BAN
CAN/B
BAN/C
ABC/N

23. Which one of the following is not an electromechanical instrument?
galvanometer
voltmeter
ammeter
AC transformer and DC generator

24. Minimum current required to produce a deflection of 1 mm on a scale at a distance of 1 meter is
0.1 A
1:00 AM
current sensitivity
1 m A

25. In a multi range ammeter as the range increases
shunt value decreases
shunt value increases
shunt value remains the same
none of the above

26. While measuring the unknown resistance the help of slide wire bridge a greatest accuracy can be achieved when
a most sensitive galvanometer is used
a steady voltage cell is used
the balance point is close to the middle of the wire
a high resistance box is used in one of its gap

27. A sensitive galvanometer gives full-scale deflection with 100 mV. If the resistance of the galvanometer is 50? the maximum current that can flow through safely is
2.0 mA
20 mA
200 mA
0.2 mA

28. An ammeter measures the total current flowing through a circuit when it is connected
in series with the circuit
in parallel with circuit
in series with any of the parallel resistances in the circuit
in parallel with any of the series resistances in the circuit

29. Coil of a galvanometer is suspended in a radial magnetic field so that the deflecting torque on the coil is always
BINA cosa
BINA sina
BINA tana
BINA

30. A galvanometer basically is an instrument used to
detect current in a circuit
measure current flowing through a circuit
measure voltage across a circuit
measure potential difference between two points in a circuit

31. The effective way to increase the sensitivity of a moving coil galvanometer is to
use a very long and fine suspension
use a coil of very large area
use a coil with very large number of turns
use a very strong magnetic field

32. A wheat stone bridge is said to be balanced when
maximum current flows through the galvanometer branch
minimum current flows through the galvanometer branch
potential difference across galvanometer branch is maximum
potential difference across galvanometer branch is zero

33. When an electron moving with a uniform speed in a vacuum enters a magnetic field in a direction perpendicular to the field the subsequent path of the electron is
a straight line parallel to the field
a parabola in a plane perpendicular to the field
a circle in a plane perpendicular to the field
a straight line along its initial direction

34. A particle of mass m charge q and speed V enters a uniform magnetic radius r. The radius r of the circle is
independent mass m
directly proportional to m
directly proportional to q
directly proportional to B

35. Galvanometer is a very sensitive device with
very low damping
very high damping
no damping at all
radial field disintegration

36. Which one of the following methods would be able to increase the sensitivity of a moving coil galvanometer ?
connect a shunt across the coil
use a coil of smaller cross sectional area
use a coil having less number of turns
use spiral springs whose force constant is small

37. Heating a magnet will
weaken it
strengthen it
reverse its polarity
demagnetize it completely

38. If a current carrying solenoid is suspended freely it will
be rotating
come to rest in N-S direction
vibrating like galvanometer needle
comes to rest after rotation