When a 12 Ω resistor is connected in parallel with a moving coil galvanometer then its deflection reduces from 50 divisions to 10 divisions. The resistance of the galvanometer is:
24 Ω
36 Ω
48 Ω
60 Ω
A voltmeter has a resistance of G ohms and range V volts. The value of resistance used in series to convert it into a voltmeter of range nV volts is :
nG
(n−1)G
Gn
G(n−1)
Which of the following statement is wrong:
Voltmeter should have high resistance
Ammeter should have low resistance
Ammeter is placed in parallel across the conductor in a circuit
Voltmeter is placed in parallel across the conductor in a circuit
The dots in the figure show a magnetic field perpendicular to the plane of the paper and coming out of it. The curve ABC shows the trajectory of a particle in the plane of the paper. What is a particle?
Proton
Electron
Neutron
It cannot be predicted
A long solenoid has 800 turns per meter length of the solenoid. A current of 1.6 A flows through it. The magnetic induction at the end of the solenoid on its axis is:
16×10-4 T
8×10-4 T
32×10-4 T
4×10-4 T
The unit of reduction factor of the tangent galvanometer is
Ampere
Gauss
Radian
None of these
In order to pass 10% of the main current through a moving coil galvanometer of 99 ohms, the resistance of the required shunt is :
9.9 Ω
10 Ω
11 Ω
9 Ω
A current-carrying closed Loop in the form of a right isosceles triangle ABC is placed in xy plane in a uniform magnetic field acting along the y-axis as shown in the figure. If the magnetic force on the arm AC is F→, then force on the arm BC and AB are respectively
zero, zero
-F→ and zero
F→ and -F→
F→ and zero
A uniform electric field and a uniform magnetic field are acting in the same direction in a certain region. If a proton is projected in this region such that its velocity is pointed along the direction of fields, then the proton :
will turn towards the left of the direction of motion
will turn towards the right of the direction of motion
will speed up
will slow down
When a proton is released from rest in a room, it starts with an initial acceleration a0 towards the east. When it is projected towards the north with a speed v0, it moves with initial acceleration 3a0 towards east. The electric and magnetic fields in the room are -
Ma0ewest, Ma0ev0up
Ma0ewest, 2Ma0ev0down
Ma0eeast, 2Ma0ev0down
Ma0eeast, 2Ma0ev0up
If the planes of two identical concentric coils are the perpendicular and magnetic moment of each coil is M, then the resultant magnetic moment of the two coil system is
M
2M
3M
Which of the following graph correctly represents the variation of magnetic field induction with distance due to a thin wire carrying current?
When an electron enters perpendicularly in a magnetic field with velocity v, time period of its revolution is T. If it enters in the same magnetic field with a velocity 2v, then its time period will be:
2T
4T
T2
T
A positively charged particle falls vertically downwards. The horizontal component of the earth's magnetic field will deflect it towards:
east
west
north
south
The magnetic dipole moment of the given loop is:
52πR2I
3πR2I
32πR2I
5πR2I
The magnetic field at center due to the orbital motion of the electron in the hydrogen atom is :
12.5 tesla
5 tesla
24 tesla
1 tesla
The figure shows a particle of charge q and mass m moving with velocity v along the x-axis enters a region of the uniform magnetic field. The minimum value of v so that the charge q is deflected by an angle 30° is
2qBb - am
qBb + a2m
qBb - am
qBb2m
An electron is traveling along the x-direction. It encounters a magnetic field in the y-direction. Its subsequent motion will be:
A circle in the xz-plane
A circle in the yz-plane
A circle in the xy-plane
A closed-loop (of any shape) carrying current is lying in the x-y plane. A uniform magnetic field B is present in the region such that the loop experiences zero force :
A galvanometer of resistance 240 Ω allows only 4% of the main current after connecting a shunt resistance. The value of shunt resistance is :
20 Ω
8 Ω
5 Ω
A moving coil galvanometer has a resistance of 50 Ωand gives full scale deflection for 10 mA. How could it be converted into an ammeter with a full scale deflection for 1A :
50/99 Ω in series
50/99 Ω in parallel
0.01 Ω in series
0.01 Ω in parallel
The resistance of an ideal voltmeter is
Zero
Very low
Very large
Infinite
The net resistance of a voltmeter should be large to ensure that :
It does not get overheated
It draws excessive current
It can measure large potential difference
It does not appreciably change the potential difference to be measured
A galvanometer having a resistance of 8 ohms is shunted by a wire of resistance 2 ohms. If the total current is 1 amp, the part of it passing through the shunt will be :
0.25 amp
0.8 amp
0.2 amp
0.5 amp
A voltmeter of resistance 1000 Ω gives full-scale deflection when a current of 100 mA flow through it. The shunt resistance required across it to enable it to be used as an ammeter reading 1 A at full-scale deflection is :
10000 Ω
9000 Ω
222 Ω
111 Ω
The ammeter A reads 2 A and the voltmeter V reads 20 V. The value of resistance R is: (Assuming finite resistance's of ammeter and voltmeter)
Less than 10 ohm
More than 10 ohm
We cannot definitely say
A galvanometer has a resistance of 25 ohm and a maximum of 0.01 A current can be passed through it. In order to change it into an ammeter of range 10 A, the shunt resistance required is
5/999 ohm
10/999 ohm
20/999 ohm
25/999 ohm
A galvanometer has 30 divisions and a sensitivity 16μA/div. It can be converted into a voltmeter to read 3 V by connecting (approximately):
Resistance nearly 6 k Ω in series
6 k Ω in parallel
500 Ω in series
It cannot be converted
A voltmeter has a range 0-V with a series resistance R. With a series resistance 2R, the range is 0-V'. The correct relation between V and V' is :
V'=2V
V'>2V
V'>>2V
V'<2V
If an ammeter is to be used in place of a voltmeter then we must connect with the ammeter a :
Low resistance in series
Low resistance in parallel
High resistance in parallel
High resistance in series
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