If an ammeter A reads 2 A and the voltmeter V reads 20 V, what is the value of resistance R? (Assuming finite resistances of ammeter and voltmeter)
     

1.	Exactly 10 ohm
2.	Less than 10 ohm
3.	More than 10 ohm
4.	We cannot definitely say

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 :

(1) $V^{\text{'}}=2V$

(2) $V^{\text{'}}>2V$

(3) $V^{\text{'}}>>2V$

(4) $V\text{'}<2V$

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 :

(1) 10000 Ω

(2) 9000 Ω

(3) 222 Ω

(4) 111 Ω

The resistance of an ideal voltmeter is 

(1) Zero

(2) Very low

(3) Very large

(4) Infinite

A galvanometer can be used as a voltmeter by connecting a :

(1) High resistance in series

(2) Low resistance in series

(3) High resistance in parallel

(4) Low resistance in parallel

A wire carrying current i is shaped as shown. Section AB is a quarter circle of radius r. The magnetic field is directed :

                                                      
(a) At an angle $\mathrm{\pi }/4$ to the plane of the paper

(b) Perpendicular to the plane of the paper and directed in to the paper

(c) Along the bisector of the angle ACB towards AB

(d) Along the bisector of the angle ACB away from AB

The earth’s magnetic field at a given point is $0.5\times {10}^{-5}Wb-m^{-2}.$ This field is to be annulled by magnetic induction at the center of a circular conducting loop of radius 5.0cm. The current required to be flown in the loop is nearly :

(1) 0.2 A                  

(2) 0.4A

(3) 4A                      

(4) 40A

A part of a long wire carrying a current i is bent into a circle of radius r as shown in the figure. The net magnetic field at the centre O of the circular loop is

(1) $\frac{{\mu }_{0}i}{4r}$                                

(2) $\frac{{\mu }_{0}i}{2\mathrm{\pi r}}\left(\mathrm{\pi }+1\right)$

(3) $\frac{{\mu }_{0}i}{2r}$                                

(4) $\frac{{\mu }_{0}i}{2\mathrm{\pi r}}\left(\mathrm{\pi }-1\right)$

What is the magnetic field at point O in the figure?
                    

1.  $\frac{{\mu }_{0}I}{4\mathrm{\pi r}}$                                  
2.  $\frac{{\mu }_{0}I}{4\mathrm{\pi r}}+\frac{{\mu }_{0}I}{2\mathrm{\pi r}}$
3.  $\frac{{\mu }_{0}I}{4r}+\frac{{\mu }_{0}I}{4\mathrm{\pi r}}$                        
4.  $\frac{{\mu }_{0}I}{4r}-\frac{{\mu }_{0}I}{4\mathrm{\pi r}}$

An electron and a proton enter a magnetic field perpendicularly. Both have the same kinetic energy. Which of the following is true:

1. Trajectory of electron is less curved

2. Trajectory of proton is less curved

3. Both trajectories are equally curved

4. Both move on a straight-line path